An image forming apparatus includes a power supply controller that selects either commercial power or a secondary battery as a power supply and a main controller that controls the power supply controller. The main controller includes a power supply availability determination unit that determines whether or not both the commercial power and the secondary battery are available and a power supply selection unit that instructs the power supply controller to select the secondary battery as the power supply during a predetermined secondary battery usage period and instructs the power supply controller to select the commercial power as the power supply at times other than the secondary battery usage period in case both the commercial power and the secondary battery are available.