An image forming apparatus includes a heating rotary member and a pressing rotary member. The pressing rotary member and the heating rotary member form a fixing nip portion and are configured to apply heat and pressure to a toner image carried on a recording medium at the fixing nip portion, thereby fix the toner image onto the recording medium. The image forming apparatus further includes a winding roller configured to wind up a web used to collect toner that is not fixed to the recording medium, a motor configured to rotate the winding roller, a contact member configured to contact an outside surface of the web wound around the winding roller, a variable resistor disposed so as to be able to change a resistance in accordance with a position of the contact member, and a control unit configured to control an amount of rotation of the motor.