No details have yet been issued from local authorities regarding the status of the workers.
Official state media outlet Xinhua reported that the workers were conducting repairs at the Zhangdang mine in the city of Fushun at the time of the midday cave-in.
Zhangdang had suspended production for the maintenance work.
The private operation employs about 240 people.
Rescuers have arrived at the scene and an investigation has begun.