An object of the invention is to provide an improved technique for lessening an impact force caused by rebound of a tool bit after its striking movement in an impact power tool. The representative impact power tool comprises a tool body, a hammer actuating member, a tool holder, a driving mechanism, a weight placed in contact with the hammer actuating member to move rearward by a reaction force transmitted from the hammer actuating member when the hammer actuating member performs a hammering operation on the workpiece and an elastic element elastically deformed when the weight moves rearward in the tool body to push the elastic element such that the elastic element absorbs the reaction force transmitted to the weight. The weight is defined one or both of the cylinder and the tool holder.