The explosion occurred as Friday prayers were underway at the mosque at Gol Chowk in Dera Bugti town.
Ahmedan Khan Bugti, a member of the National Assembly or lower house of parliament, and several worshippers were among the injured, police officials said.
The injured were taken to two nearby hospitals.
Officials said some of them were in a serious condition.
Police officials the bomb was planted outside the wall of the mosque.
No group claimed responsibility for the attack.
