To reduce the weight and size by connecting a commercial power supply to an input side, connecting coils for an electromagnetic brake to an output side, arranging a rectifying device between one end of the input side and one end of the output side, and arranging a switchgear between the other end of the input side and the other end of the output side.

A motor brake power supply feed part 7 closes a motor brake releasing switch contact 7-a, or a switchgear as necessary and a power supply halfwave rectified using a diode 7-b, or a rectifying device is fed to coils 4-to 4n (n is a number of coils present) of an electromagnetic brake for locking a motor shaft so that the lock of the motor shaft is released. The power supply formed by rectifying the commercial power supply by the rectifying device is used as the power source of the electromagnetic brake and the power supply is turned on/off via a motor brake releasing switch contact so that this device can save the space and be economical.