An image forming apparatus includes: an image forming unit; a first sheet discharging path that reverses a traveling direction of a sheet and discharges the sheet; a cover, which forms a part of the first sheet discharging path when the cover is in a closed state; a second sheet discharging path, which is formed when the cover is in an open state, which is branched from the first sheet discharging path, and which discharges the sheet from the image forming unit without reversing the traveling direction of the sheet; a sensor, which is positioned downstream in a conveying direction of the sheet from the image forming unit, and which detects a passage of the sheet; and a determination unit that determines a jam based on a detection result of the sensor, the determination unit changing a determination criterion of the jam in accordance with the state of the cover.