A power tool includes a housing, a prime mover disposed in the housing, a first cylinder formed with a first chamber, a first rotating member rotatable with respect to the first cylinder about a first axis under the driving of the prime mover, a first piston movable in a direction parallel to the first axis when the first rotating member rotates relative to the first cylinder. The first cylinder and the first rotating member are disposed within the housing. The first piston is disposed within the first chamber The first rotating member is formed with a first transmission structure to drive the first piston The first piston is formed with a second transmission structure capable of cooperating with the first transmission structure to rotate the first rotation member to drive the first piston.