According to Japan Meteorological Agency, the temblor was centered in the northern part of the Ibaraki prefecture, with the epicentre at a latitude of 36.7 degrees north and a longitude of 140.6 degrees east and at depth of 10 km, Xinhua news agency reported.
The earthquake logged lower 6 on the Japanese seismic intensity scale which peaks at 7 in some parts of Ibaraki prefecture, and could be felt in a wide range of areas in eastern and northeastern Japan including Tokyo.
No tsunami warning has been issued, and two people were sent to hospital for minor injuries.
No abnormalities were observed at the Tokai No. 2 nuclear power plant in Ibaraki as well as in two nuclear power plants in Fukushima Prefecture, according to their operators.
The weather agency warned that another earthquake with a similar magnitude might occur in the following week.