To achieve the functions of a micro-engine hand-piece and of an air-turbine hand-piece by one hand-piece, and to perform the cutting requiring torque by using the torque of a micro-motor while performing the cutting requiring high-speed rotation by using the rotation of an air turbine.

The hand-piece 1 has a rotating barrel 10 inside a head 2, and turbine blades 11 to which air is blown and a gear 13 to be engaged and rotated with a gear 15 rotated by a motor disposed inside the hand-piece 1. In the cutting requiring the torque, the gears 13 and 15 are engaged with each other and the rotating barrel 10 (a cutting bar 3) is rotated by the motor. In the cutting requiring the high-speed rotation, the engagement of the gears 13 and 15 is released, and the hand-piece is rotated by the turbine blades 11.