A first frame includes a pair of first roller-receiving portions which rotatably supports a convey roller. A second frame is attached to the first frame and includes an extending portion which extends beyond one of the first roller-receiving portions toward one side of the convey roller in its axial direction. A third frame includes a base portion, and a first side wall and a second side wall which are opposite to each other. The first and second side walls are attached to the extending portion so as to he perpendicular to the axial direction of the convey roller. The first side wall is disposed more toward the one side of the convey roller in the axial direction than the second side wall and includes a portion which receives a shaft of a motor for the convey roller, and a second roller-receiving portion which rotatably supports the convey roller.