The blast shook the Wayaobao Coal Mine in Yanan on Saturday after a gas build-up in the mine ignited, Xinhua said.
Unlike many smaller mines across China, this one had all the necessary production and safety permits, the report said.
This latest tragedy is just one of thousands every year that make China's mines the most dangerous in the world.
More than 3,300 coal mine blasts, floods and other accidents claimed nearly 6,000 lives across the country last year, as mine owners - motivated by soaring profits - pushed production past safe limits to fuel the booming economy.
The head of the national coal mine safety watchdog said in early April that China would shut down all coal mines with an annual output under 30,000 tons by the end of 2007.
The Wayaobao mine produced 31,000 tonnes in 2005, Xinhua reported.
But safety officials have acknowledged that the crackdown on unsafe mines has run into considerable resistance from owners and from local officials who often have a lucrative stake in them.