A controller includes a failure detection unit that detects a failure in a first power supply system, and a power supply system control unit that closes a relay in a case where an execution of an automatic parking function starts and, during the execution of the function, causes the first power supply system to supply power, without causing a second power supply system to supply power, to the electric brake device, by setting a target output voltage of the second power supply system lower than an output voltage of the first power supply system when the failure detection unit does not detect the failure, and operates the electric brake device by setting the target output voltage to a voltage within a range in which the electric brake device is operable when the failure detection unit detects the failure.