A control device is applied for a power supply system that includes two boost converters. The two boost converters boosts inputted direct-current voltages to predetermined output voltages and output ends of the two boost converters are connected in parallel with each other. The control device includes a switching portion and a control portion. The switching portion controls switching of a switching element included in each of the two boost converters. The control portion shifts switching timings of the switching elements of the two boost converters from each other.