An image forming apparatus includes a transfer unit, a fixing unit, and a control unit. The transfer unit transfers a toner image onto a sheet. The fixing unit fixes the toner image onto the sheet and includes a roller. The control unit controls a roller rotational speed. Where both a first loop amount of the sheet at one side in a width direction orthogonal to a sheet conveyance direction and a second loop amount of the sheet at the other side in a width direction are within a predetermined range, the control unit switches a roller rotational speed for controlling a loop amount of the sheet between the transfer unit and the fixing unit. Where either the first or second loop amount is not within the predetermined range, the control unit sets the roller rotational speed into a predetermined speed without switching the roller rotational speed.