PURPOSE: To prevent the occurrence of braking force in position instruction of an industrial robbot, etc., by providing a dead zone to produce no braking force in a crawling rotation area by the use of the forward voltage drop of diodes in a motor generation braking circuit.

CONSTITUTION: In generation braking, the current of a relay coil 16 is cut off to get relay contacts 14 and 15 on side B, so that a DC motor 11 is short- circuited by a discharging resistance 13 through silicon diodes 18∼21. When the rotating speed gets below the predetermined value, the braking current is cut off by the diodes 18∼21 and the braking force becomes zero. In driving, on the other hand, the relay contacts 14 and 15 are switched to side A, so that the DC motor 11 is connected to a motor drive circuit 12.