A method of operating a rotary tool driven by a brushless motor including a DC brushless motor for rotationally driving a rotary bit, a torque setting clutch mechanism, a drive switch for drive-controlling a drive control circuit of the brushless motor, and a control means to rotationally drive the brushless motor by an operation of the drive switch and wherein the method includes a first step for stop-controlling of the drive control circuit, a second step for rotating forward or in reverse the brushless motor through the control and a third step for control-operating a semiconductor of an inverter circuit provided in the drive control circuit to short-circuit the magnetizing windings of the brushless motor, thus braking the rotor of the brushless motor and stopping the brushless motor.