Tokyo and its suburbs were jolted by a strong earthquake with an estimated magnitude of 6.1 late on Thursday, Japan's public broadcaster NHK reported.
It registered a tremor of "5 plus" on Japan's own scale of quake intensity, a level that could cause some damage to buildings and cause power cuts. Several bullet train lines were halted due to the quake, the broadcaster said.
Initial information from the JMA put the epicentre of the quake in Chiba prefecture, east of Tokyo, and said it struck at 10:41pm (1341 GMT) with a depth of 80 kilometres. There were no immediate reports of injuries or damage.
The quake was comparatively strong compared to recent quakes in Tokyo, which like much of Japan regularly experiences seismic activity.
Newly elected Prime Minister Fumio Kishida in a tweet urged residents to "please take action to save lives while checking the latest information."
The country is regularly hit by quakes and has strict construction regulations intended to ensure buildings can withstand strong tremors.
Last week, a 6.1-magnitude quake struck off Japan´s northwestern coast, also causing no damage.
