An earthquake with preliminary magnitude of 6.2 jolted Tokyo and vicinity early Monday morning, the Japan Meteorological Agency said. There was no tsunami warning and no immediate reports of major damage, Reuters reported.
The epicenter was 160 km below the ocean just south of Tokyo.
At least one local train line was halted but TV broadcasts showed cars moving normally in the capital.
There were no reports of trouble at nuclear power plants in the vicinity, public broadcaster NHK said.