The unnamed boss drowned during a rescue operation, according to China Central Television.
Seventeen miners remained trapped two days after the gypsum mine collapsed in Shandong province, state media reported.
Structural instability and falling rocks were hindering the efforts of 700 rescuers using heavy machinery to dig along existing shafts to reach them, the Xinhua news agency reported.
A miner whose leg was stuck under a boulder was brought to safety early Saturday morning, bringing the total rescued to seven, the agency reported. Four other miners found their own way out on Friday.
Survivor Zhai Guangmong recalled Friday's collapse when he and 28 others were working at the mine.
"After the cave-in, I could see nothing at all," he told Xinhua.
Gypsum is a soft grey or white mineral used in tofu, fertilizers, toothpaste and plaster of Paris.
DPA