|Storm Usman hit the Bicol region southeast of capital Manila on Saturday.
At least 17 people are missing and the death toll is expected to rise.
One official told AFP news agency that people did not take precautions as it was not classed as a typhoon under the
government's alert system.
"People were overconfident because they were on vacation mode and there was no tropical cyclone warning," Bicol civil
defence director Claudio Yucot said.
Although the storm did not have strong winds, it brought heavy rains which triggered deadly landslides.
The tropical depression has destroyed infrastructure and displaced more than 40,000 people nationwide.
Tropical storms regularly batter the Philippines.
Typhoon Mangkhut, the strongest tropical cyclone of the year, wracked the island nation with winds of winds of 200km/h
(125 mph) in September.
More than 60 people died in the typhoon, many buried in landslides in Benguet province north of Manila.
The deadliest storm on record in the Philippines was Super Typhoon Haiyan in 2013, which also sparked category four
It killed more than 7,000 people and affected millions.