An image forming apparatus is provided that detects a sheet remaining between a transfer unit and fixing unit using a loop sensor. The loop sensor is configured to detect a loop of a sheet conveyed between the transfer unit and the fixing unit. The image forming apparatus includes a control unit to control, in accordance with an output from the loop sensor, a sheet conveyance speed of the fixing unit so as to form the loop of the sheet conveyed by the transfer unit and the fixing unit. If the loop sensor detects a presence of the sheet while driving of the transfer unit and the fixing unit for conveying the sheet has stopped, the control unit determines that a remaining sheet is present, and outputs a warning signal.