Patent ID: 7756456

Claim:
An image forming apparatus comprising: a belt member stretched across at least two rollers, each of the at least two rollers including a first end portion and a second end portion; a protrusion disposed, such that it protrudes along the traveling direction of the belt member, on an inner surface of one edge side of the belt member; an engagement portion that is formed in the first end portion of the rollers and with which the protrusion is engageable; and a plurality of image carriers arranged in a line, wherein each image carrier carries a toner image transferred to a recording medium conveyed by the belt member or the surface of the belt member, wherein the second end portion of one roller of the at least two rollers is shifted with respect to the first end portion of the one roller in a direction away from and orthogonal to the line of the image carriers, and the second end portion of an other roller of the at least two rollers is not shifted with respect to the first end portion of the other roller in a direction away from the image carrier; and wherein the second end portion of one roller is drawn away from the line of the plurality of image carriers and the first end portion of the one roller is not drawn away from the line of the plurality of rollers.