PURPOSE: To enhance the working efficiency by allowing a memory and command means to store the revolving position in the condition a revolving member is in operation, regenerating by a regeneration command means, and by putting the revolving member into regenerative operation.

CONSTITUTION: When a memory and command means 11 is operated in the condition a revolving member 1 is in operation, switching elements 14, 20 are changed over, and the revolving position is sensed by a position sensing means 10. Then the signal thus obtained is fed into No.1 memory part 15, and at the same time, an operation signal from an operation command means 6 is fed into No.2 memory part 21 to be stored as operation command signal. When a regeneration command means 12 is operated, switching means 16, 19, 22 are changed over, and a signal from the No.1 memory part 15 is added to a signal from the sensing means 10 at an adding device 17. The signals from these adding device 17 and No.2 memory part 21 are fed into another adding device 23, whereto a signal from the switching element 19 is added, and the sum obtained is entered into a drive signal converting means 24. With the drive signal a driving means 5 put the revolving member 1 into regenerative operation.