Government minister Steve Mbikayi said a further three people had been taken to hospital with serious injuries. Search efforts are continuing.
The accident occurred at a mine in the town of Kampene on Wednesday.
Accidents are common in DR Congo's informal mining sector which has poor safety standards.
Mr Mbikayi said in a tweet that the death toll from Wednesday's accident was provisional.
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Civil society campaigner Justin Kyanga Asumani said the accident happened at about 14:00 local time (13:00 GMT) at the illegal mine in the province of Maniema.
He said "dozens of people, including children and pregnant women" were working on the site when the mine collapsed.
In June dozens of miners were killed when a copper and cobalt mine in DR Congo's Lualaba province collapsed.
Reserves of cobalt and other minerals like diamonds, copper and gold, should make DR Congo one of the richest countries in Africa, but its people are among the poorest.