The Japanese Meteorological Agency (JMA) has reportedly issued a tsunami advisory following the 7.0 quake.
Witnesses described moderate to strong shaking throughout southern Japan.
"Get out of the water and leave the coast immediately," the JMA said in a statement. "As the strong current will continue, do not get in the sea or approach coast until the advisory is cleared."
The US Geological Survey measured the quake as a magnitude 7.1, and located its epicenter 99 miles west-southwest of Makurazaki, at a depth of 6.2 miles.
The Pacific Tsunami Center has stressed that there is no threat of a tsunami.