An image forming apparatus including a transfer belt on which an image is transferred, a belt suspension roller that suspends the transfer belt, a transfer roller that is arranged to face the belt suspension roller with the transfer belt in between and includes a shaft portion and a concave portion formed in a shaft direction, and a support member that is arranged on the shaft portion of the transfer roller and includes a first circumferential portion arranged in the concave portion as seen from a shaft direction of the transfer roller, a second circumferential portion arranged at one side of the concave portion in a rotation direction, and a third circumferential portion arranged at the other side of the concave portion in the rotation direction.