The ruling Democratic Party of Japan, or DPJ, announced the election date. Kan had earlier offered to resign if two key bills dealing with government bond issue and renewable energy are approved by Parliament by Friday, Kyodo News reported.
The party president normally becomes the prime minister.
DPJ Secretary General Katsuya Okada told a news conference Monday official campaigning for party president will begin Saturday.
Kan, who became prime minister only in June of last year, has been under pressure to resign over his government's handling of the nuclear crisis at the Fukushima Daiichi nuclear power plant triggered by the March 11 earthquake and tsunami.
Earlier reports have said Kan's DPJ and the main opposition Liberal Democratic Party have planned to get the bills passed by Friday, paving the way for Kan's resignation.