Kyodo cited the country's Meteorological Agency as saying that the earthquake occurred at around 14:25 GMT with a magnitude of 5.5 on the Japanese seismic intensity scale of 7. The agency added that the earthquake occurred in waters off Iwate's northern coast at a depth of about 12.5 miles.
The agency said that there was no threat of a tsunami despite the significant magnitude.
There are no immediate reports of casualties or any damage caused by the earthquake.