The quake hit at 8:31 pm (1701 IST) about 110 kilometres east of Fukushima near the east coast of Honshu at a depth of 30 kilometres, the Japan Meteorological Agency said.
No tsunami warnings were in effect and there were no immediate reports of damage.
The northeast coast of Japan's main Honshu island was ravaged by a 9.0 magnitude quake and monster tsunami on March 11 which left more 23,000 people dead or missing.
The disasters also crippled the Fukushima Daiichi nuclear power plant, triggering the world's worst atomic accident since Chernobyl in 1986 and forcing hundreds of thousands of residents to leave their homes.
Published 18 June 2011, 13:33 IST