An ECU for controlling a starter includes a transistor in addition to transistors, which turn on relays provided for a pinion gear and a motor of the starter, respectively. The transistor is provided in a current path, which connects a line of a battery voltage and a junction between upstream side ends of coils of the relays. The ECU operates the starter by turning on the three transistors, which turn on the relays. It further detects abnormality based on voltages of terminals.