The quake struck at 5:24 pm (0824 GMT) in Fukushima prefecture at a depth of 10 kilometres (six miles), according to the Japan Meteorological Agency.
Tokyo Electric Power, which operates the Fukushima plant, said the quake did not adversely affect the site of the worst atomic accident since Chernobyl.
Seismologists say the area will continue to feel strong aftershocks from the monster 2011 quake, which unleashed a deadly tsunami that swamped reactor cooling systems and devastated Japan's northern Pacific coastline.
The disaster left more than 18,000 people dead or missing and sparked the nuclear crisis at Fukushima.
On Saturday a strong 6.8-magnitude earthquake off the coast near Fukushima caused a minor tsunami in the early hours, though authorities lifted all warnings roughly two hours later.