According to reports, Shinzo Abe entered Keio University hospital on 17 August in the morning.
The specific reason for the Japanese PM's hospital visit was not revealed. Kyodo reported, citing unnamed sources, that Abe visited the hospital for a regular check-up.
Abe's hospital visit comes amid speculation over his health, as Kyodo said that Abe's alleged 'check-up' follows a comment by Economy Minister Akira Amari, who remarked that "the prime minister needs some rest".
According to Kyodo, a local weekly magazine earlier reported that Abe had "vomited blood" in July.
In 2007, Abe abruptly resigned as prime minister, with one reason behind the move said to have been poor health. He later announced his recovery and returned to office in 2009.