An image forming apparatus includes: an image forming unit configured to form an image on a paper sheet; a conveying unit configured to convey the paper sheet to the image forming unit at a first conveyance speed and convey the paper sheet in the image forming unit at a second conveyance speed; a trouble detecting unit configured to detect a trouble; and a control unit configured to control the conveyance of the paper sheet in the conveying unit and the image formation on the paper sheet in the image forming unit, wherein, when the trouble detecting unit detects a trouble from the paper sheet being conveyed, and the control unit controls the conveying unit to perform a purging process to discharge a troubled paper sheet to the outside of the apparatus, the control unit controls a conveyance speed to be equal to the second conveyance speed.