Khush Dil Khan escaped unhurt in the blast on the outskirts of Peshawar, the main city in the north-west.
Islamist militants are fighting a vicious war against Pakistani security forces in and around Peshawar, which lies close to border regions with Afghanistan where extremists hold sway.
Police said the attacker managed to get inside the compound where funeral prayers were being held in Badhber village. Peshawar deputy commissioner Siraj Ahmad said the explosion killed 15 people and wounded another 37.
The Pakistani Taleban have targeted several of the Awami National Party leaders in the past. The party has supported various Pakistani military operations against the militants.
On Saturday, security forces claimed to have killed 39 militants in fighting in Bara district in Khyber tribal region, which is close to Peshawar and is the current focus of anti-Taleban operations. Four security force members were also killed, according to a brief statement from the paramilitary Frontier Corps.