PURPOSE: To prevent malfunction at address change with simple constitution by applying an output of a ROM directly to a drive circuit as a drive signal.

CONSTITUTION: A storage data of the ROM 1 is read according to an address 4 and fed tb a drive circuit 3 comprising an inverter I, a resistor R and a transistor(TR). The TR in the drive circuit 3 is turned on/off according to the output of the ROM 1 to control whether or not an operating current is fed to the relay 2. The relay 2 has an integration characteristic and even when the drive signal fed to the drive circuit 3 is changed, the state is not immediately changed and the time after the drive signal changes till the state of the relay 2 changes is far longer than the address change period. Thus, the malfunction of the relay at address change is prevented with economical constitution.