To reduce heat generated in consuming regenerative energy generated from a motor in deceleration operation while reducing a series of operation times of a robot without changing the control content of a drive control means to control the drive of the motor.

A step-up/down circuit 29 executes either of a step-up operation of stepping up an input voltage to a step-up value to be output and a step-down operation of stepping down the input voltage to be output. When a motor M is driven based on an operation pattern in which a deceleration operation is executed without passing through a constant-speed operation after an acceleration operation, a control part 27 controls the operation of the step-up/down circuit 29 to execute a step-up operation in a step-up period from the starting point of the acceleration operation to changeover timing of the ending stage of the acceleration operation, and to execute a step-down operation in a step-down period from the changeover timing to the starting point of the next acceleration operation. The control part 27 determines the length of the step-up period by obtaining the changeover timing by calculation.