PURPOSE: To prevent a supply voltage drop due to the generation of overcurrents in a holding-current supply circuit by mounting a holding-current control circuit turning the holding-current supply circuit OFF during the generation period of back electromotive force when a drive-current supply circuit is changed over to an OFF state from an ON state.

CONSTITUTION: When a control circuit 4 detects timing to an OFF state from an ON state for a fixed time T of a switch element Trl by a Trl ON-N signal, the control circuit 4 issues a command to a timer circuit 5 so that a timer output signal is altered to '1' from '0' after a time T'' passes while a switch element Tr3 is turned OFF. The time T,, is set so as to hold T''>T', to an experimentally obtained back electromotive force generation period T'. When a timer circuit 5 outputs '1' after the time T'' passes, the control circuit 4 turns the switch element Tr3 ON, and resets the timer circuit 5. The control circuit 4 continuously controls the switch element Tr3 under the ON state during periods except said operation.