There is provided an image forming apparatus which can implement on-demand fusing with quick rise in temperature by using the upper current (power) limit of a commercial power supply more effectively. This image forming apparatus includes a rechargeable battery device capable of charging and discharging, and is designed such that a driven load other than a heating element of a fusing device can receive power a commercial power supply and/or the rechargeable battery device. When printing is to be executed, the commercial power supply and rechargeable battery device are controlled as power supply sources for the driven load. The power supplied from the commercial power supply to the fusing device is then limited to a limit level corresponding to the control result.