An image forming apparatus having a process correction mode wherein when a temperature of a fixing device in an image formation system in a power-on state is equal to or less than a predetermined value, the image forming apparatus increases the fixing temperature to the predetermined value. The apparatus sets the process correction mode based on power-on information output from a first detector which detects presence of the power-on state for the fixing device and fixing temperature information output from a second detector which detects a fixing temperature in the fixing device, and sets a priority level for performing a correction processing of the color misregistration to be lower than a correction processing comprising an image density adjustment.