The invention provides a power tool capable of effectively avoiding an increase in size while performing vibration damping action in working operation, which comprising a motor; an internal mechanism driven by the motor; a housing consisting of an inner housing for housing the internal mechanism and provided with an upper housing and a lower housing, and an outer housing for housing the inner housing and the motor and provided with a motor shell and a crank shell; a tool bit mounted at one end of the housing and driven by the internal mechanism in a longitudinal direction to perform a predetermined operation; a handgrip connected with the other end of the housing; and a dynamic vibration reducer including a cylindrical vibration reducer body, a weight and an elastic element. The axial direction of the motor is crossed with the longitudinal direction of the tool bit. The elastic element is disposed between on the front and rear side surfaces of the weight and is adapted to apply a spring force on the weight. The weight reciprocates in the longitudinal direction of the tool bit against the spring force of the elastic element. The dynamic vibration reducer is disposed by utilizing an internal space defined by the housing and/or the handgrip. The dynamic vibration reducer reduces the vibration generated in the housing along the longitudinal direction of the tool bit during the working operation.