An image forming apparatus includes: an apparatus body including: an image forming unit that forms toner images having the colors being different from each other; a intermediate transfer body that has a belt-shape, and that is arranged in an upper portion of the image forming unit being inclined with respect to the horizontal direction, the toner images being transferred onto the intermediate transfer body; an intermediate transfer body unit that detachably holds the intermediate transfer body with respect to the apparatus body; and a guide rail member that detachably guides the intermediate transfer body unit in a direction of one side of the apparatus body, and that is set so that the direction, in which the intermediate transfer body unit is guided, is changed in the middle of guiding.