PURPOSE: To improve safety of a motor not to generate traction while a brake command is issued by a method wherein a series circuit composed of diodes and contactors which is turned on by a brake command is connected in parallel to an armature.

CONSTITUTION: A series circuit including a contactor 11 and a diode 12 which is turned on by the brake command is connected in parallel to an armature 1. In the range wherein a brake command is given, a contactor 11 is closed and an armature activates effectively as a regeneration brake, a terminal AA becomes positive against a terminal A, as a result, current does not flow in the diode 12. On account of some reason, however, when a braking mode is still maintained after the stop of a rolling stock, then, power is supplied from a power source 8 to the armature, whereas, the armature 1 is short-circuited by means of the diode 12. On this account, the power supplied from the power source 8 flows in the diode 12 but is not given to the armature 1, as a result, traction is not generated in the armature 1, thus, improper behavior such as travelling of a rolling stock in the opposite direction can be prevented.