The quake occurred at 11:05 am (0405 GMT) with an epicentre 69 kilometres southwest of Labuha city, the Indonesian Meteorological and Geophysics Agency said. It struck at a depth of 10 kilometres.
The US Geological Survey recorded the quake's magnitude at 6.6 and put the quake's depth at 19 kilometres.
"We haven't received any reports of damage. The tremor was also felt in the neighbouring city of Ternate," the agency's official Ajat Sudrajat told AFP, adding that there was no threat of a tsunami.
A 6.0-magnitude earthquake jolted the Indonesian resort island of Bali last month, injuring dozens of people and triggering panic as tourists fled violently shaking buildings.
Indonesia sits on the Pacific "Ring of Fire", where the meeting of continental plates causes high volcanic and seismic activity.
