PURPOSE: To increase the operationability, by enabling to set and reset with the back up power supply consisting of cells, through the provision of the memory element of one bit unit, in the controller such as copy machines.

CONSTITUTION: When the switch So of the AC power supply E is closed, the rectified output voltage V1 of the main power supply circuit 1 is fed to the entire controller. Taking the voltage of the back up battery Ba as V2 and V1>V2, the voltage V1 is fed to the data memory element 2 and to the FF circuit 4 which the diodes D1 and D2, and the signal transmittal is made via the control unit 5 between each unit. If a failure such as jam is taken place, the set signal in one bit unit is set to the FF circuit 4 from the unit 5 and the output signal is inputted to the unit 5 and required control is made. When the switch So is disconnected, the data memory element 2 and the FF circuit 4 are backed up with the battery Ba and the memory content is held as it is. Since the memory content before can be used as it is even with the reapplication of the switch So, the operationability is excellent.