An image forming apparatus includes: a drum unit having an image carrier carrying a toner image; a fixing unit having a heating member and pressure member forming a fixing nip part with the heating member and fixing the toner image on a recording medium at the fixing nip part; a cooling duct provided between the drum unit and the fixing unit preventing heat transfer from the fixing unit to the drum unit; and a cooling fan causing the air to flow to the cooling duct. The cooling duct is a movable duct being changeable to a first state in which the cooling duct is unopen towards the fixing unit and a second state in which the cooling duct is open towards the fixing unit. The cooling duct changes to the first state during image formation by the drum unit and changes to the second state after the image formation.