A startup operation control apparatus includes a main-power-source operation unit, a determining unit, a memory, and a controller. The main-power-source operation unit is operated to supply and shut off power from a power source. The determining unit determines whether or not the main-power-source operation unit has been operated. The memory stores, every time an operation mode of a processing device that operates by receiving power supply from the power source changes, information representing the changed operation mode in an updating manner. If the determining unit determines, upon a shift from a power shutoff state to a power supply state, that the main-power-source operation unit has not been operated, the controller performs control so that the processing device operates in the operation mode represented by the information stored in the memory.