PURPOSE: To reduce the wear of a brake shoe and to improve the power regenerative rate by switching a generative brake control when a load of a trolley line decreases during the regenerative brake control.

CONSTITUTION: When a load is sufficient at the trolley line side, the power of an induction motor 6 is regenerated through a 3-phase inverter 4, condenser 3 and reactor 2 for a filter to the trolley line side. When the load at the trolley side decreases so that the voltage of the condenser 3 rises, a signal is outputted from a voltage detector 8, thereby firing a switching control element of a generation brake current controller 13, and a part of the power of the motor 6 is consumed at a resistor 10. In this manner, the switching between the regenerative brake control and the generative brake control is performed automatically, continuously and reversibly in response to the load state of the trolley side. Accordingly, the wear of a brake shoe can be reduced, and the power regenerative rate can be improved.