Finance Minister Masajuro Shiokawa has been diagnosed as having acute gallbladder inflammation caused by gallstones, ministry officials said Thursday.
The 81-year-old Shiokawa was hospitalized Wednesday and is expected to remain there for about a week, the officials said.
He was in stable condition after undergoing treatment Wednesday evening, they said.
Shiokawa canceled a trip to Thailand to attend a meeting of finance ministers of the Asia-Pacific Economic Cooperation forum starting Thursday after experiencing stomach problems.