A driving section generates rotational driving force and has an output shaft that outputs the rotational driving force. An end-bit mounting section holds an end bit and is rotatable about a rotational axis. A friction clutch is provided between the end-bit mounting section and the driving section. The friction clutch includes a drive member and a follow member. The drive member rotates together with the driving section and has a drive-side contact surface. The follow member rotates together with the end-bit mounting section and has a follow-side contact surface contactable with the drive-side contact surface. The friction clutch is movable between a transmission position where frictional force is produced between the drive-side contact surface and the follow-side contact surface so that the output shaft and the end-bit mounting section can rotate together, and a cutoff position where the output shaft and the end-bit mounting section are non-rotatable together.