A hammer-drive powder-actuated tool includes: a barrel unit inserted movably into a tubular housing; a firing pin holder disposed fixedly in the housing, abutting against a rear end portion of the barrel unit and formed with a through hole; a firing pin disposed movably between a rear open end of the housing and the rear end portion of the barrel unit, having an intermediate portion interconnecting integrally a firing end portion that extends into the through hole in the firing pin holder and a head portion, and operable between a normal position and a firing position; an engaging member sleeved on the intermediate portion of the firing pin for stopping movement of the firing end portion of the firing pin away from the through hole in the firing pin holder; and a biasing member for biasing the firing pin to move toward the normal position.