The earthquake occurred at around 1:08 a.m. on Saturday (about 16:08 GMT on Friday) near the island of Kyushu, with the epicentre located at a depth of 40 kilometres (24.8 miles), according to the Japan Meteorological Agency. No tsunami warning was issued.
The prefectures of Miyazaki, Oita, Kochi, and Kumamoto registered tremors of up to five on the Japanese seven-point seismic intensity scale, the Kyodo news agency said.
According to the media, at least six people were injured, most of them slightly, in Oita Prefecture. In Miyazaki, four injuries were registered. Casualties have also been reported in the Saga and Kumamoto prefectures.
The exact number of those injured is yet to be determined, the news agency said.