An image forming apparatus, wherein a heating member heats a toner image formed on a sheet by an image forming portion, including: a first detector detecting a temperature of a first area of a contact area, which is contactable with the sheet, of the heating member, when a set width of the sheet is a predetermined width; a controller for controlling the heating member based on the output of the first detector; a second detector detecting a temperature of a second area outside of the first area; a cooler cooling the second area based on the output of the second detector; a third detector detecting a temperature of a third area on an end side in the width direction within the contact area; and a stopper stopping the image heating operation based on the output of the third detector.