A tsunami of 20 centimetres was observed at 5.12am local time in Ishinomaki, Miyagi prefecture, the Japan Meteorological Agency said.
The agency had issued a tsunami advisory for Miyagi as well as for neighbouring Fukushima and Iwate prefectures, warning that a ave of up to one metre could affect their Pacific coastlines after the quake.
Large areas of the coastline covered by the advisory are still recovering from the 2011 quake and tsunami disaster that killed more than 18,000 people and triggered a meltdown at the Fukushima Daiichi nuclear plant.
Plant operators Tokyo Electric Power (TEPCO) said there were no immediate reports of abnormality after Saturday's quake.
"We have not seen any damage or any change in radiation gauges after the quake," said TEPCO spokesman Masahiro Asaoka.
"Today's operation has yet to start but we ordered workers to evacuate to high places," Asaoka said.
The meteorological agency advised people to leave the coast immediately, while Japan's public broadcaster NHK said some local authorities had issued evacuation advisories.
The United States Geological Survey said the quake struck around 129 kilometres east southeast of the city of Namie, 284 kilometres east northeast of the capital Tokyo, at 4.22am local time.
The Fukushima plant's cooling systems were swamped by the 2011 tsunami, sparking reactor meltdowns and radiation leaks in the worst atomic crisis in a generation.
Tens of thousands of people were evacuated from around the plant, with decommissioning of the site expected to take decades.The utility is struggling to handle a huge - and growing - volume of contaminated water.
On Friday, the crippled plant was skirted by tropical storm Neoguri. Workers had scrambled to insulate the plant from any damage, but the storm had little impact.
Japan is at the conjuncture of several tectonic plates and experiences a number of relatively violent quakes every year.
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