He served as parliamentary vice minister of agriculture under the premiership of Kiichi Miyazawa but left the LDP in 1993 to join the Japan Renewal Party.

[2] As prime minister, Ishiba almost immediately announced a snap general election, where the ruling LDP coalition lost its majority for the first time since 2009 and suffered its second-worst result in party history.

[12][14] Ishiba was reappointed parliamentary vice minister of Agriculture under the Mori Cabinet in July 2000 but was switched to the position of deputy director general of the Defense Agency in December.

He defended the legality of the invasion and paved the way for the first overseas deployment of the Japanese Self-Defense Forces without UN mandate, sending troops to Iraq in January 2004 to assist with reconstruction efforts.

[25] Ishiba attracted considerable criticism for his statement in November 2013 that likened peaceful public protests against the new secrecy bill being introduced by his government to "acts of terrorism".

[27] In the September 2014 cabinet reshuffle, Abe moved Ishiba from his position as LDP Secretary-General and appointed him to a newly created office of Minister for Overcoming Population Decline and Vitalizing Local Economy.

[33] 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.

[40][41] 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.

[44][45] 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.

[48] 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.

[56] 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.

[60] 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."

[61] 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.

[75][76] 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.

[88] In February 2025, Ishiba said that the government would consider offering medical care for sick and wounded residents of the Gaza strip, amidst Israel's war with Hamas that has been ongoing since October 2023.

[90] In February 2025, Defense Minister Gen Nakatani revealed that the Self-Defense Forces would provide approximately 30 additional transport vehicles to the Ukrainian military.

While he was cited as a member of the ultranationalist far-right organisation Nippon Kaigi,[101][102][103] he has been criticized by nationalist commentators for his "traitorous acts",[104] and for being "anti-Japan",[105] and has pointed to Japan's failure to face its war responsibilities as underlying "many of its problems".

[108][109] On 17 December 2024, Prime Minister Shigeru Ishiba made the following statement about same-sex marriage during a parliamentary session: “I have met concerned individuals, and I can see that being together is the most precious thing to them.

[99] On election night, Ishiba called on the LDP to propose a supplementary budget for the 2024 fiscal year, aimed at financing a stimulus package to help rural areas cope with rising costs.

[119] In September 2024, Ishiba claimed that the "relative decline of U.S. might" necessitates an Asian version of NATO to counter security threats from China, Russia, and North Korea.

[117] Indian External Affairs Minister Subrahmanyam Jaishankar also does not agree with Ishiba's idea for an Asian NATO as it does not fit with India's strategic goals.

[120] Following his victory in the 2024 LDP presidential election, some South Korean media outlets have described Ishiba as a "dove" in regards to his perception of Japan's accountability in World War II.

They should be held accountable for that", and similarly saying that "I cannot understand why their actions that led to the defeat of the country, without giving accurate answers to Emperor Shōwa's questions and without informing the public of the truth, are being left unquestioned as 'we are all heroes once we die.

[136][7] Ishiba is known as an "otaku" with a very high interest in the military, vehicles, and trains, and keeps a large collection of military-related plastic models, some of which are displayed at his office in the Diet.

[137] He is also a fan of the 1970s idol group Candies, is known to ride on sleeper trains to Tottori Prefecture as part of his interest in railways, and regards novelists Soseki Natsume and Ogai Mori as two of his favorite authors.

[18] Ishiba made headlines when he allowed a Japan Self-Defense Forces vehicle to be displayed at the Shizuoka Hobby Show, a trade fair for plastic and radio-controlled models.

During the visit of former United States Ambassador to Japan Howard Baker in 2002, Ishiba presented a plastic model of the Lockheed P-3 Orion in their meeting at his office.

When the Russian Defence Minister visited Japan, Ishiba was said to be have stayed up all night assembling a plastic model of the aircraft carrier Admiral Kuznetsov.