An image forming system includes an image forming apparatus that forms an image on a sheet and a peripheral device that is connected to the image forming apparatus. The image forming system includes an electrical power supply unit, a driving unit, a secondary battery that is charged with electrical power from the electrical power supply unit, an electrical power changing device that activates or deactivates a first supply path for supplying electrical power from the electrical power supply unit to the secondary battery and activates or deactivates a second supply path for supplying electrical power from the secondary battery to the driving unit, and a controller unit that controls the electrical power changing device so as to deactivate the first supply path and activate the second supply path when initialization of the image forming system is performed.