Videos of Mr Abe being driven in a car to Keio University Hospital in Tokyo on Monday were widely shown on Japanese TV news reports.
Public broadcaster NHK TV later showed him leaving the hospital.
The prime minister’s office declined to comment on the hospital visit, saying it was not on his official schedule.
Mr Abe has been on a summer break recently, as has much of Japan.
A governing party politician, Akira Amari, remarked on television over the weekend that Mr Abe feels guilty about taking time off but needs rest.
Mr Abe, 65, has had health concerns before.
He stepped down in 2007 during an earlier stint as prime minister, citing health problems.
Kyodo News said the visit was part of a regular checkup Mr Abe gets about twice a year.
Although Mr Abe sometimes goes to his summer home in the countryside about this time of year, he has stayed in Tokyo amid widespread concerns about the coronavirus pandemic, according to Kyodo.
Mr Abe is the longest-serving prime minister in Japanese history.
