Shigeru Ishiba's tenure as prime minister of Japan began on 1 October 2024 when he was officially appointed prime minister by Emperor Naruhito in a ceremony at the Tokyo Imperial Palace, succeeding Fumio Kishida.

Ishiba stood in the 2024 Liberal Democratic Party presidential election to succeed Kishida, who announced he would not seek re-election as LDP leader following record-low approval ratings from an ongoing slush fund scandal and previous controversies with the LDP's affiliation with the Unification Church. Ishiba alongside Sanae Takaichi and Shinjirō Koizumi emerged as the frontrunners to succeed him. In the leadership election on 27 September 2024, Ishiba narrowly defeated Takaichi in a second-round runoff. Ishiba's victory was described by commentators as unexpected and an upset, owing to his long history of failed leadership bids and his relative unpopularity with many LDP members of the National Diet.

As prime minister, Ishiba almost immediately announced a snap general election, where the ruling LDP and Komeito coalition lost its majority in the House of Representatives for the first time since 2009, suffering its second-worst result in party history. In the National Diet, Ishiba relied on opposition parties to pass legislation due to his coalition's minority government status. He worked with the opposition Japan Innovation Party to pass the 2025 fiscal year budget. In March 2025, he faced a scandal when it was revealed several LDP members of parliament who were elected for the first time in the 2024 election received gift certificates from the office of Ishiba in early March, causing a decline in his popularity. On foreign policy, Ishiba moved Japan economically closer to India and South Korea amidst protectionist policies being employed by the United States, while continuing to support Ukraine during the Russian invasion that began in 2022. He also saw an improvement of relations with China.

After the ruling coalition lost its majority in the House of Councillors after a poor result in the 2025 election, Ishiba began to face calls within the LDP for him to resign. Ishiba initially announced he planned to remain as prime minister, citing the need to see through tariff negotiations with the United States. After a trade deal between the two nations were announced on 23 July, it was erroneously reported that Ishiba would resign at the end of August. He eventually announced his intention to resign as party president and as prime minister in September 2025, and was succeeded as prime minister by Takaichi the next month.

LDP presidential bid

Then-LDP leader and prime minister Fumio Kishida announced on 14 August 2024 that he would not seek re-election as LDP leader in the leadership election in September, effectively resigning as prime minister, following record-low approval ratings from an ongoing slush fund scandal and previous controversies with the LDP's affiliation with the Unification Church. Ishiba alongside Sanae Takaichi and Shinjirō Koizumi emerged as the frontrunners to succeed him. In the leadership election on 27 September 2024, Ishiba narrowly defeated Takaichi in a second-round runoff, winning a total of 215 votes (52.57%) from 189 parliamentary members and 26 prefectural chapters, making him the new LDP leader and prime minister–designate; the election was dubbed "Ishibamania" by the foreign media.

Ishiba's victory was described by commentators as unexpected and an upset, owing to his long history of failed leadership bids and his relative unpopularity with many LDP members of the National Diet. After his election, the Japanese stock market experienced a sudden drop in response to Ishiba's economic policies, which was named "Ishiba Shock". Three days after the LDP presidential election, the new party officials under Ishiba were inaugurated. Ishiba appointed former Prime Minister Yoshihide Suga vice president of the party, while the outgoing Vice President Tarō Asō was made chief advisor, and Hiroshi Moriyama became secretary general. Shun'ichi Suzuki was made chairman of the General Council after Takaichi declined the post. Itsunori Onodera was made chairman of the Policy Research Council and Shinjiro Koizumi chairman of the Election Strategy Committee. The appointments were seen as emphasizing stability in the party.

On 30 September, Ishiba announced his plans to dissolve the House of Representatives on 9 October and called for snap general election to be held on 27 October 2024. This decision, which was announced before he was elected Prime Minister by the Diet, drew criticism from opposition parties as it did not allow time for a debate at a budget committee meeting prior to the House's dissolution. Despite this resistance, the Lower House voted in favor of closing the extraordinary Diet session on 9 October.

Premiership

Ishiba was elected by the National Diet and appointed as Prime Minister by Emperor Naruhito at Tokyo Imperial Palace on 1 October 2024, becoming the twenty-fifth Liberal Democratic Prime Minister. Ishiba announced key appointments ahead of the snap general election on 27 October 2024. His Cabinet included rivals from the leadership race, though Sanae Takaichi's exclusion created internal party friction. Uniting the divided ruling party became a primary focus for Ishiba after the closely contested leadership race.

In his first policy speech on 4 October, Ishiba named Japan's low birth rate and the regional security situation as among his primary concerns, describing the former as a "quiet emergency" and the latter as at its "most severe since the end of World War II". He also pledged to continue efforts to ensure the emergence of the Japanese economy from deflation and called for stabilization in the membership of the Imperial House of Japan amid a lack of male successors to the throne. He also expressed regret for the 2023–2024 Japanese slush fund scandal.

2024 general election and Second cabinet

On 9 October, Ishiba dissolved the House of Representatives in preparation for the general election on 27 October. On the same day, the LDP decided to pull its endorsement of 12 politicians implicated in the slush fund scandal, and would not allow them to be elected via proportional representation should they lose in their single seat constituencies. Ishiba indicated that the party would resume support for the politicians if they win reelection. Other politicians who have been disciplined by the party over the slush fund scandal would also not be allowed to run on the LDP's proportional representation list.

Despite these measures, LDP still faced its most serious defeat since the 2009 election, with 68 seats lost and therefore its majority in the Diet. On the next day, Ishiba expressed his intention to remain as Prime Minister despite the election results. Commentators noted that his decision for the snap election election may jeopardize his leadership, as rising inflation and a funding scandal threaten his LDP's majority, prompting potential alliances with smaller parties amid growing economic concerns.

On 11 November, Ishiba was reelected as prime minister of a minority government during a session of the Diet, after winning a total of 221 votes from both the first and second rounds, defeating Yoshihiko Noda of the Constitutional Democratic Party of Japan, who secured only 160 votes, following a second round runoff vote. Hours before the Diet assembled, Ishiba's first cabinet resigned, thus resulting in him making an effort to launch a second cabinet. However, it was agreed that his cabinet would mostly remain the same. Ishiba's re-election would also mark the first time in 30 years that any Japanese prime minister needed a runoff vote.

Domestic policy

During the opening ceremony of the 217th ordinary session of the Diet, Ishiba's government submitted a draft budget for the new fiscal year 2025 with the general account at over 115 trillion yen, the largest ever. The unprecedentedly large budget was attributed to social security expenses related to the aging population and the strengthening of defense capabilities that began under the previous Kishida administration. On 24 January he delivered a policy speech, proclaiming his ideal for a "fun Japan" where everyone "feels safe and secure, and people with diverse values respect each other and strive for self-realization." He also said he would prioritize regional revitalization, addressing the gender pay gap, and digitalization among other issues.

In February 2025, Ishiba worked with the opposition Japan Innovation Party to pass the 2025 fiscal year budget. The budget included provisions that called for free high school education and social insurance premium fee cuts. The agreement was signed by the LDP, Komeito, and Ishin on 26 February.

Social issues Ishiba's government announced in January 2025 that same-sex partners will be subject to the same regulations as common-law marriages in 24 laws, including one that stipulates benefits to be paid to the families of crime victims. Consideration for legislation allowing separate surnames for married couples also began in the LDP under Ishiba's presidency. Ishiba's former rival, Sanae Takaichi, urged him to approach the topic with "caution" during internal party deliberations. He has remained hesitant about introducing same-sex marriage legislation.

Foreign policy

Ishiba was elected as Prime Minister during the closing months of Joe Biden's presidency in the United States, meeting with him at the APEC summit in Peru in November 2024, alongside South Korean President Yoon Suk Yeol. Later in January 2025 he held a virtual meeting with Biden and Philippine President Bongbong Marcos during which the three agreed to strengthen ties and cooperation. After Donald Trump won the 2024 presidential election, Ishiba congratulated him publicly, stating he would like to meet with him soon in his capacity as President-elect. Unlike his late former rival Shinzo Abe, Ishiba was not able to meet with Trump during his transition period.

After Trump's inauguration, he sent him a congratulatory letter, in which he emphasized the importance of a free and open Indo-Pacific. By February a meeting was set up between the two; Ishiba stated that he would explain to Trump Japan's high investment in the United States and its contributions to US job creation, mirroring a strategy implemented by Abe to negotiate with Trump when he was prime minister. Ishiba sought the advice of Abe's widow, Akie Abe, along with former Prime Minister Fumio Kishida before the meeting. He said he would seek to form a “personal relationship” with Trump. Nevertheless, Ishiba and Trump were referred to as an “odd couple” by National Review and The Economist.

United States

Ishiba arrived in Washington D.C. on 6 February, along with translator Sunao Takao, who had previously assisted Shinzo Abe communicate with Trump during his tenure as prime minister. Takao was described as an “important asset” to Ishiba, given he is "probably one of the few Japanese people that Trump remembers." Ishiba met with Trump the following day at the White House, where the two held a meeting followed by a press conference. During the meeting, Ishiba praised Trump, describing him as “very sincere.” He also referenced the attempted assassination of Trump that occurred in July 2024, and drew similarities between their domestic regional revitalization policies.