To effectively suppress the vibration of a blade in an electromotive circular saw.

In the electromotive circular saw equipped with the drive gear 133 provided to a rotary shaft 135 on a drive side rotated through an electromotor, the rotatable rotary shaft 143 on a follower side arranged in parallel to the rotary shaft 135 on the drive side, the follower gear 147 provided to the rotary shaft 143 on the follower side to be meshed with the drive gear 133 and the blade 123 mounted on the rotary shaft 143 on the follower side, the elastic rings 151 and 153 mutually frictionally locked with the drive gear 133 and the follower gear 147 are provided and the relative movement in the peripheral direction between the drive gear 133 and the follower gear 147 caused by the backlash between the drive gear 133 and the follower gear 147 is suppressed by the frictional locking of the elastic rings 151 and 153. By this arrangement, the vibration of the blade 123 associated with the rapid change in the rotational speed of the blade 123 due to backlash can be suppressed.