A power tool having a gear speed reducing mechanism which is free of backlash and a planetary gear speed reducing mechanism. The planetary gear speed reducing mechanism has a driving-side member that is rotationally driven by a prime mover, a driven-side member which is rotatably and coaxially disposed with the driving-side member and to which a tool bit is coupled, and an intervening member which is disposed between the driving-side member and the driven-side member. The intervening member is configured as a planetary member and at least caused to rotate by frictional force acting on its contact surface in contact with the driving-side member when the driving-side member is rotationally driven, so that torque of the driving-side member is transmitted to the driven-side member at reduced speed.