An intermediate transfer unit includes an intermediate transfer belt, a driving roller, a tension roller, and a roller supporting frame. The roller supporting frame includes first and second supporting frames, and has a coupling portion formed on it. The coupling portion includes a rotary shaft and a shaft hole. The roller supporting frame shifts from a first state to a second state by rotating the first supporting frame in the forward direction to have the intermediate transfer belt wound around it. The rotary shaft includes a projection. A shaft hole has a restricting wall portion. As the first supporting frame in the second state rotates in the forward direction, the projection makes contact with the restricting wall portion to restrict rotation of the first supporting frame in the forward direction.