The present invention achieves miniaturization. In an impact wrench 10, a speed reduction mechanism 60 includes a carrier part 62 integrally formed at a rear end of a spindle 42, and a planetary gear 66 rotatably supported on the carrier part 62, the planetary gear 66 being engaged with a pinion gear 31A of a motor 30. Moreover, the speed reduction mechanism 60 has a bearing 70 for rotatably supporting the carrier part 62, and the bearing 70 is disposed on a radially outer side of a drive shaft 31 of the motor 30, relative to the planetary gear 66. Therefore, compared to a hypothetical configuration in which the carrier part 62 were rotatably supported by the bearing 70 disposed on the front side or the rear side of the planetary gear 66, it is possible to miniaturize the physique of the speed reduction mechanism 60 in the front-rear direction, and to consequently miniaturize the physique of the impact wrench 10 in the front-rear direction. Thus, the front and back distance between a workpiece and a worker can be shortened.