An earthquake with preliminary magnitude 5.4 jolted Wakayama prefecture in western Japan today, the Meteorological Agency said, but there were no immediate reports of casualties or damages and no tsunami warning was issued.
The earthquake caused strong shaking in the area near the epicentre, to the south of Japan's third-largest city of Osaka.
The focus of the quake, at 7.18pm, was six miles below the surface in northern Wakayama, west of Tokyo.
No nuclear power plants are located near the epicentre.
A 9.0-magnitude quake and tsunami on March 11 devastated areas along the Pacific coast in northern Japan and triggered the world's worst nuclear crisis since Chernobyl 25 years ago.
Engineers are still struggling to bring the reactors under control.