An image forming apparatus includes a housing, a detection unit provided in the housing to detect temperature or humidity, an image forming section provided in the housing and including a detected portion to be detected by the detection unit, a first air inlet provided in the housing, a suction unit that sucks air outside of the housing through the first air inlet, a substantially cylindrical duct provided at a position influenced by temperature or humidity of the detected portion and including an entrance from which air flows in and an exit from which air flows out, the duct allowing the air sucked by the suction unit to pass therethrough, and an opening provided in the housing. The detection unit is provided at a position on a path of air flowing into the housing through the opening and on a path of the air that has passed through the duct.