An image forming apparatus for forming an image on a recording material includes: an image forming portion for forming the image on the recording material; a fixing portion, including a cylindrical rotatable member having a heat generating layer, for fixing the image on the recording material by heat of the rotatable member; and a temperature detecting portion for detecting a temperature of the rotatable member. The temperature detecting portion monitors a temperature change amount during one rotation of the rotatable member. The rotatable member is heated by the heat generating layer generating heat by a flow of a current in a circumferential direction of the rotatable member. Depending on the temperature change amount, a notification of an abnormality of the image forming apparatus is generated.