An image forming apparatus includes a printing unit capable of printing, the printing unit being in a suspended state with power supply being cut off in power-saving mode, and being in a wait state with power being supplied thereto in normal mode; an information storage unit capable of writing and retaining setting information of the printing unit at the time of power supply, the information storage unit being in a suspended state with power supply being cut off in power-saving mode; and a signal control unit that controls power supply to the information storage unit in power-saving mode with a signal transmitted and received by an interface unit from an external terminal device.