An impact wrench is provided that can mitigate vibrations in the axial direction without reducing the rotary impact force of hammers. The hammers are composed of a primary hammer fitted to the outer circumference of a spindle and a cylindrical secondary hammer that is disposed so as to cover the primary hammer and that rotates integrally with the primary hammer. Furthermore, the secondary hammer is held by a center holding means in a state in which the rotational axis of the secondary hammer is coincident with the axis of the spindle in order to prevent run-out movement. With the use of the hammer configuration of the present invention, the mass of the primary hammer can be decreased compared to that of the secondary hammer, and therefore it is possible to mitigate vibrations in the axial direction while maintaining the rotary impact force.