A housing includes a first frame which includes a first accommodating portion having a bottom plate to be supported on a predetermined support surface, the first accommodating portion having an accommodating space for accommodating the image reading part, and a second accommodating portion protruding outward in a first direction from a side surface of the first accommodating portion, the second accommodating portion positioned higher than the bottom plate, the second accommodating portion having an accommodating space for accommodating the operation unit; a second frame attached to a peripheral edge portion of an opening formed on a top surface of the first accommodating portion; and an engaging mechanism installed at the side of a base end portion of the second accommodating portion and configured to bring the second accommodating portion and the second frame into engagement in a direction perpendicular to the side surface of the first accommodating portion.