PURPOSE: To reduce the dropping distance of a shaft at the time of emergency stop by shortening a period of time from the output of an emergency stop signal to the OFF of a conduction control transistor(Tr).

CONSTITUTION: Since the Tr of a photocoupler PC1 is turned OFF when an emergency stop switch SW1 is operated, the collector current of the TrQ1 of an interrupter 4 is interrupted. As a result, the base voltage of a TrQ2 is reduced and the TrQ2 is turned OFF. Thus, a conduction control TrQ3 is forcible turned OFF, the current of a solenoid L is interrupted, and a DC brake, not shown, is operated. In the case of an emergency stop switch SW2, a DC brake is similarly operated. By operation of the emergency stop switches SW1 or SW2, a period of time from the output of the emergency stop signal to the OFF of the TrQ3 is approx. 10μsec, and the dropping distance of a shaft in a gravity direction is reduced as compared with that of a conventional one.