“Now that a conclusion has been reached in the negotiations concerning the US tariff measures, I believe this is precisely the appropriate time,” Ishiba said, referring to a deal signed last week to ease tariffs imposed by US President Donald Trump on Japanese cars and other exports.
Until Sunday, he had resisted calls to resign, saying it was his responsibility to settle the dispute with Washington before stepping down.
“I have strongly believed that negotiations concerning the US tariff measures, which could be described as a national crisis, must be brought to a conclusion under our administration’s responsibility,” he said.
The 68-year-old said he would continue his responsibilities “to the people” until a new prime minister was selected.
Ishiba, who took office in October 2024 promising to tackle rising prices, struggled to inspire confidence as the country faced economic headwinds, a cost-of-living crisis and fractious politics with the US.
Inflation, particularly the doubling of rice prices in the past year, was politically damaging.
Public support further slid after a series of controversies, including criticism of his decision to appoint only two women to his cabinet and handing out expensive gifts to party members.