An image forming apparatus includes a belt member; a first drum for bearing a toner image to be transferred onto the belt member; a second drum, provided downstream of the first drum with respect to a rotational direction of the belt member, for bearing a toner image to be transferred onto the belt member; a first steering portion, provided upstream of the first drum with respect to the rotational direction of the belt member, for controlling a widthwise position of the belt member; and a second steering portion, provided downstream of the second drum with respect to the rotational direction of the belt member, for controlling the widthwise position of the belt member with a delay of a movement time of the belt member from the first drum to the second drum.