An image forming apparatus includes: an image forming device; a fixing device including a fixing unit configured to fix a toner image to a recording sheet; a first AC receiving portion configured to receive power for the image forming device from an AC power source; a second AC receiving portion configured to receive power for the fixing device from the AC power source; a third AC receiving portion, which is removably connected to the image forming device, and is configured to receive power to be supplied to the fixing unit via the first AC receiving portion; and a connection detecting portion configured to detect whether power is supplied from the third AC receiving portion to the fixing device. The image forming device detects whether the third AC receiving portion is connected to the image forming device based on a detection result of the connection detecting portion.