Patent ID: 8045913

Claim:
An image forming apparatus comprising: a main body; an optional tray that is mountable to a lower part of the image forming apparatus, a fastening depression formed at a lower part of the main body of the image forming apparatus and a penetrating hole formed at a flank thereof in communication with the fastening depression, wherein the optional tray comprises a tray body; a print medium supply tray that is insertable into and removable from the tray body; a connection boss that protrudes from an upper part of the tray body and that inserts into the fastening depression; a key member that restrains escape of the connection boss from the fastening depression; a key hole formed in connection boss that receives the key member, the key member passing through the penetrating hole and being inserted into the key hole; and a clip member to restrain the key member from escaping from the key hole, wherein the key member comprises a clip groove formed around an outer circumference thereof, and the clip member comprises a resilient part that engages with the connection boss and resiliently encloses the clip groove.