A power supplying mode switching controller is disclosed. The power supplying mode switching controller includes a main controller which controls an image forming apparatus, a power supply circuit which has a normal mode and a power saving mode, an I/O controller which switches the power supply circuit to the normal mode when a factor returning to the normal mode is generated in the power saving mode, and an SD interface to which an SD card is attached. The I/O controller includes a first attaching change detecting circuit which detects an attaching change of the SD card to the SD interface, and when the first attaching change detecting circuit detects the attaching change of the SD card to the SD interface in the power saving mode, the I/O controller switches the power supply circuit to the normal mode and informs the main controller of the attaching change of the SD card.