The government will give the go-ahead to Osaka Prefecture's bid to host the 2025 World Exposition, sources said.
Japan is estimating that the event, which is to be held between May and November 2025, will bring economic benefits worth ¥1.90 trillion ($17.18 billion) over a six-month period.
The Cabinet is set to formally approve the bid in a meeting on April 11, the sources said on Tuesday.
The country will submit its application to the expo's governing body, the Bureau International des Expositions, in April. Osaka will be pitted against Paris, where the BIE's headquarters is located.
An economy ministry advisory panel is compiling a final report, titled "Designing Future Society for Our Lives," in which it has proposed to hold the event on the artificial island of Yumeshima.
Japan is planning to push its bid at the BIE's general meetings in June and November and during an inspection that will be held next year.
A key strategy in winning the bid will be to attract broad support from 168 member nations in a meeting that will be held in November 2018.
If Japan should win, the expo will be held soon after the 2020 Olympics and Paralympics, repeating the pattern of the 1964 Tokyo Games and 1970 Expo, which was also held in Osaka.
Japan also hosted the expo in 2005 in Aichi Prefecture.