The explosion happened when worshipers were busy in evening prayers, the provincial governor’s spokesman Arif Noori said.
He said that 20 others were wounded in the explosion which was as a resulted of an embedded explosive device inside the Mohammadiya mosque in Khak-e-Ghariban area in the city of Ghazni.
No group has claimed responsibility for the attack.
Ghazni has recently witnessed heavy clashes between government forces and the Taliban. Last month, the Afghan forces retook the control of Deh Yak district in the province which was under the Taliban influence for almost two years.