PURPOSE: To improve safety, by operating a brake unit through utilization of a base block signal outputted from a microprocessor.

CONSTITUTION: A motor brake 11 having a brake coil 12 is driven through an inverter 13. The inverter 13 rectifies and smoothes AC power fed from a power source 14 through a rectifier 15 and a capacitor 16 then inverts the smoothed power into DC power through a switching element 17. A control circuit therefor comprises a DC power source circuit 18, an operating circuit 19, a protection circuit 20, a microprocessor 21 and a base driver 22, and controls the element 17. The operating element 19 receives a free-run stop signal from a relay switch 24, and a base block signal is outputted from the microprocessor 21 according to the free-run stop signal. The protection circuit 20 disables the switching element 17 upon occurrence of over current. Brake unit is operated on the base block signal so as to synchronize ON/OFF timing of the output from the inverter 13 and the brake timing reliably.