The is a
political party in Japan that was established in 1996. Since its reformation and name change in 1996, it has advocated
pacifism
Pacifism is the opposition to war or violence. The word ''pacifism'' was coined by the French peace campaigner Émile Arnaud and adopted by other peace activists at the tenth Universal Peace Congress in Glasgow in 1901. A related term is ...
and defined itself as a
social-democratic party.
It was previously known as the .
The party was re-founded in January 1996 by the majority of legislators of the former Japan Socialist Party, which was the largest opposition party in the
1955 System. However, most of those legislators joined the
Democratic Party of Japan
The was a Centrism, centristThe Democratic Party of Japan was widely described as centrist:
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after that. Five leftist legislators who did not join the SDP formed the
New Socialist Party, which lost all its seats in the following election. The SDP enjoyed a short period of government participation from 1993 to 1994 as part of the
Hosokawa Cabinet and later formed a coalition government with the
Liberal Democratic Party under 81st
Prime Minister
A prime minister or chief of cabinet is the head of the cabinet and the leader of the ministers in the executive branch of government, often in a parliamentary or semi-presidential system. A prime minister is not the head of state, but r ...
Tomiichi Murayama of the JSP from 1994 to January 1996. The SDP was part of ruling coalitions between January and November 1996 (
First Hashimoto Cabinet) and from 2009 to 2010 (
Hatoyama Cabinet).
In the
2019 Japanese House of Councillors election, the party won four representatives in the
National Diet, two in the lower house and two in the upper house. In November 2020, the party entered into a merger agreement with the
Constitutional Democratic Party (CDP) with the SDP's members in the Diet caucusing with the CDP. The party president Mizuho Fukushima held her seat and, in the
2022 House of Councillors elections, the party cleared the minimum two percent voter share to maintain its legal political party status.
History
Before 2000
In 1995, the former Japan Socialist Party (JSP) was in a deep crisis, facing criticism for entering a coalition with its long-time rival, the LDP and for core policy changes. Aiming at saving the party, the leadership of JSP decided to dissolve the party and to establish a new social democratic party. In January 1996, a new party, the Social Democratic Party, was established, along with the dissolution of JSP. ''
De jure
In law and government, ''de jure'' (; ; ) describes practices that are officially recognized by laws or other formal norms, regardless of whether the practice exists in reality. The phrase is often used in contrast with '' de facto'' ('from fa ...
'', JSP changed its name to the Social Democratic Party (SDP) as an interim party for forming a new party, and a movement for transforming the SDP into a new social-democratic and liberal party was unsuccessful.
Under Murayama's successor
Ryūtarō Hashimoto (LDP), the SDP remained part of the ruling coalition. Long before its disappointing result in the
1996 Japanese general election, the party lost the majority of its members of the House of Representatives, mainly to predecessors of the
Democratic Party of Japan
The was a Centrism, centristThe Democratic Party of Japan was widely described as centrist:
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* to Centre-left politics, centre-left, Liberalism, liberal or Social liberalism, social-liberal List of political parties in Japan, ...
(DPJ) that was formed in 1996, but also some to the NFP and other opposition parties. After its electoral defeat in the 1996 general election, when it lost another 15 of its remaining 30 seats in the lower house, the SDP left the ruling coalition, which it had entered as the second-largest force in Japanese politics, as a minor party.
2000s–2010s
The SDP won six seats in the
2003 Japanese general election, compared with 18 seats in the previous
2000 Japanese general election. The party's opposition to the Self-Defense Forces reverted to the abolition of the forces in the long term, the policy it had in the 1950s. Doi had been the leader since 1996, but she resigned in 2003, taking responsibility for the election losses.
Mizuho Fukushima was elected as the new party leader in November 2003. In the
2004 Japanese House of Councillors election, the SDP won only two seats, having five seats in the
House of Councillors
The is the upper house of the National Diet of Japan. The House of Representatives (Japan), House of Representatives is the lower house. The House of Councillors is the successor to the pre-war House of Peers (Japan), House of Peers. If the t ...
and six seats in the
House of Representatives
House of Representatives is the name of legislative bodies in many countries and sub-national entities. In many countries, the House of Representatives is the lower house of a bicameral legislature, with the corresponding upper house often ...
. In 2006, the party unexpectedly gained the governorship of the
Shiga Prefecture. In the
2009 Japanese general election, the DPJ made large gains and the SDP maintained its base of 7 seats in the, becoming a junior partner in a new government coalition; however, disagreements over the issue of the
Futenma base led to the sacking of Fukushima from the cabinet on 28 May and the SDP subsequently voted to leave the ruling coalition.

As of October 2010, the SDP had six members in the House of Representatives and four members in the House of Councillors. Following the
2012 Japanese general election, the party retained only six seats in the whole of the Diet, two in the House of Representatives and four in the House of Councillors. The count lowered to five seats in 2013. In 2013, the party's headquarters in Nagatacho, where the party's predecessor the JSP had moved in 1964, were demolished. The headquarters moved to a smaller office in Nagatacho.
During the nomination period of the
2016 Japanese House of Councillors election, the party signed an agreement with the
Democratic,
Communist
Communism () is a sociopolitical, philosophical, and economic ideology within the socialist movement, whose goal is the creation of a communist society, a socioeconomic order centered on common ownership of the means of production, di ...
and
People's Life parties to field a jointly-endorsed candidate in each of the 32 districts in which only one seat is contested, thereby uniting in an attempt to take control of the House from the LDP/
Komeito coalition. The party had two Councillors up for re-election and fielded a total of 11 candidates in the election, 4 in single and multi-member districts and 7 in the 48-seat national proportional representation block.
In the
2017 Japanese general election, the party managed to hold to its two seats it had prior to the election.
Tadatomo Yoshida declined to run for re-election when his term expired in January 2018.
Seiji Mataichi was elected unopposed in the
ensuing leadership election and took office on 25 February 2018.
Since 2020
On 14 November 2020, the party voted to agree to a merger arrangement with the
Constitutional Democratic Party of Japan (CDP), allowing members to leave the SDP and join the latter party. The majority of the party supported the agreement and joined the CDP; however, party leader Fukushima herself was opposed to the merger agreement and remains a member of the Social Democratic Party.
In the
2021 Japanese general election, the party lost one of their two seats.
Policies
Party policies include:
* Defend
Article 9 of the Constitution of Japan and
declare cities defenseless so that they will not resist in the event of invasion.
* Advocate a significant increase in the scope of
social welfare
Welfare spending is a type of government support intended to ensure that members of a society can meet basic human needs such as food and shelter. Social security may either be synonymous with welfare, or refer specifically to social insurance p ...
such as
healthcare
Health care, or healthcare, is the improvement or maintenance of health via the preventive healthcare, prevention, diagnosis, therapy, treatment, wikt:amelioration, amelioration or cure of disease, illness, injury, and other disability, physic ...
,
pensions,
social security
Welfare spending is a type of government support intended to ensure that members of a society can meet basic human needs such as food and shelter. Social security may either be synonymous with welfare, or refer specifically to social insurance ...
and
disability
Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be Cognitive disability, cognitive, Developmental disability, d ...
care.
* Opposition to
neoliberalism
Neoliberalism is a political and economic ideology that advocates for free-market capitalism, which became dominant in policy-making from the late 20th century onward. The term has multiple, competing definitions, and is most often used pe ...
and
neoconservatism.
* Complete disarmament of Japan in accordance with
pacifist principles. The
Japanese Self-Defense Force will be replaced with a force dedicated to disaster relief and foreign aid.
* Cancellation of the
United States–Japan military alliance, dismantling of
United States bases in Japan and replacing it with a
Treaty of Friendship.
* Introduction of an environmental
carbon tax.
* Significant increase in the scope of wildlife protection legislation, increasing the number of
protected species and setting up of protection zones.
* Transition from a mass-production/mass-consumption society to a sustainable society in coexistence with nature.
* Clampdown on harmful chemicals, e.g. restriction on use of agricultural chemicals, ban on
asbestos
Asbestos ( ) is a group of naturally occurring, Toxicity, toxic, carcinogenic and fibrous silicate minerals. There are six types, all of which are composed of long and thin fibrous Crystal habit, crystals, each fibre (particulate with length su ...
, tackling
dioxin and soil pollutants.
* Increased investment in public transport, encouraging a switch from road to rail and from petrol powered buses to hybrids, electric vehicles and
light rail transit.
* Opposition to
nuclear power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by ...
and proposal of a gradual switch to
wind energy as the nation's base energy source.
* Abolition of the
death penalty
Capital punishment, also known as the death penalty and formerly called judicial homicide, is the state-sanctioned killing of a person as punishment for actual or supposed misconduct. The sentence ordering that an offender be punished in s ...
.
* Opposition to
water privatization.
* Supports
feminist
Feminism is a range of socio-political movements and ideology, ideologies that aim to define and establish the political, economic, personal, and social gender equality, equality of the sexes. Feminism holds the position that modern soci ...
politics.
* Legalization of
same-sex marriage
Same-sex marriage, also known as gay marriage, is the marriage of two people of the same legal Legal sex and gender, sex. marriage between same-sex couples is legally performed and recognized in 38 countries, with a total population of 1.5 ...
.
[Inada, Miho; Dvorak, Phred]
"Same-Sex Marriage in Japan: A Long Way Away?"
. ''The Wall Street Journal''. September 20, 2013. Retrieved March 31, 2014.
Leaders
Election results
House of Representatives
House of Councillors
Current Diet members
House of Representatives
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Kunio Arakaki (
Okinawa-2nd)
House of Councillors
Up for re-election in 2025
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Yūko Ōtsubaki (
National PR)
Up for re-election in 2028
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Mizuho Fukushima (
National PR)
See also
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Democratic Party of Japan
The was a Centrism, centristThe Democratic Party of Japan was widely described as centrist:
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* to Centre-left politics, centre-left, Liberalism, liberal or Social liberalism, social-liberal List of political parties in Japan, ...
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Democratic Socialist Party (Japan)
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Japan Socialist Party
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Leftist Socialist Party of Japan
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List of political parties in Japan
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Politics of Japan
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Rightist Socialist Party of Japan
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Itsurō Sakisaka
Notes
References
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External links
Official website
{{authority control
1996 establishments in Japan
Centre-left parties in Asia
Democratic socialist parties in Asia
Environmentalism in Japan
Feminist parties in Asia
Full member parties of the Socialist International
Left-wing parties in Japan
LGBTQ political advocacy groups in Japan
Pacifism in Japan
Pacifist parties
Political parties established in 1996
Progressive parties in Japan
Social democracy in Asia
Social democratic parties in Japan