Electric tool

The invention provides an electric tool. The electric tool includes a motor, a decelerator, and a reduction ratio changing mechanism. The speed reducer comprises a multi-stage planetary gear mechanism. The reduction ratio changing mechanism changes the reduction ratio of the speed reducer according to the change of the rotation direction of the motor shaft. At least two stages of the multi-stage planetary gear mechanism are configured such that the respective internal gears selectively function as fixed structural elements. The reduction ratio changing mechanism has a one-way clutch and a lock mechanism. When the one-way clutch does not transmit rotation, the lock mechanism locks the at least two stages of internal gears so as not to rotate, and when the one-way clutch transmits rotation, the lock mechanism rotates the at least two stages of internal gears. The at least two stages of planetary gear mechanisms comprise a speed increasing planetary gear mechanism and a speed reducing planetary gear mechanism. T