PURPOSE: To execute safety ensuring operation in simple construction and low power consumption in case of emergency by outputting a control signal in an ordinary way for control operation, and by outputting a failure signal when a malfunction detection signal is inputted.

CONSTITUTION: Control operation is performed by outputting control signals 21a∼21d in an ordinary way. When a malfunction detection signal is inputted or emergency arises inside a controller 21, the second failure signal is outputted for operation. When an excess current breaker 18 breaks a circuit by emergency such as short circuit arised on load side, or when the output of the third power source 19a is stopped by failure of the third power source supplier 19, the first failure signal is outputted. Or, when malfunction arises in a voltage generator 15 or the controller 21, the second failure signal is outputted. As a result, a fuel supplier 14 executes safety ensuring operation for the minimum of time required. Therefore, safety ensuring operation is executed in simple constitution and low power consumption.