An image forming apparatus of the present invention includes a resin frame composed of a resin and an image forming unit that is removably inserted in the resin frame. The resin frame includes a base having a supporting surface that supports the image forming unit, a guide portion that extends in the base in an insertion direction in which the image forming unit is inserted along the supporting surface and that guides the image forming unit in the insertion direction while limiting movement of the image forming unit in an orthogonal direction that is orthogonal to the insertion direction, and a side plate portion that is provided at a peripheral edge of the base so as to extend in a direction perpendicular to the supporting surface, the base, the guide portion, and the side plate portion being integrally molded from a resin. A mold opening direction of a mold for molding the guide portion is set to a direction parallel to the orthogonal direction, and downstream end portions of the side plate portion in the mold opening direction are integrally connected to each other and extend essentially parallel to the perimeter of the base.