The shallow quake struck at about 2:00 pm (0600 GMT), a few kilometres from Maragusan municipality in the mountainous gold-mining province of Davao de Oro on Mindanao island.
Shallow earthquakes tend to cause more harm than deeper ones, but there were no immediate confirmed reports of major damage.
An employee in the Maragusan disaster office told AFP that authorities were checking reports of a landslide on a national highway.
"We have not received any reports of other damage or casualties, but we are checking the villages around the town," he added, declining to give his name.
"Things shook at the office but there was no damage."
The quake lasted about 30 seconds and was followed by aftershocks, said Corporal Stephanie Clemen, with police in the city of Tagum, about 40 kilometres (25 miles) from Maragusan.
"We immediately went under our desks and when the ground stopped shaking we went straight outside," Clemen told AFP.
"We are still outside because a moderate aftershock just hit."
While the quake did not appear to have destroyed anything, Clemen said, it was strong enough to "cause fear".
Phoebe Alberto and her colleagues at the disaster office in New Bataan municipality, adjacent to Maragusan, fled their building as it shook.
"We are still assessing damage to our building, if any," said Alberto.
"We are here outside now."
Quakes are a daily occurrence in the Philippines, which sits along the Pacific "Ring of Fire", an arc of intense seismic as well as volcanic activity that stretches from Japan through Southeast Asia and across the Pacific basin.
Most are too weak to be felt by humans, but strong and destructive ones come at random with no technology available to predict when and where they will happen.
The nation's civil defence office regularly holds drills simulating earthquake scenarios along active fault lines.
The last major quake was in October in the northern Philippines.
The 6.4-magnitude earthquake hit the mountain town of Dolores in Abra province, injuring several people, damaging buildings and cutting power to most of the region.
A 7.0-magnitude quake in mountainous Abra last July triggered landslides and ground fissures, killing 11 people and injuring several hundred.
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