Accessory device and electronic device including the same

An electronic device comprising:

• a housing comprising a first housing which is moveable relative to a second housing, in an expansion direction away from the second housing to define an expanded area of the first housing and in a retraction direction toward the second housing;
• a display module connected to the housing, the display module extendable in the expansion direction to define an expanded area of the display module, and retractable in the retraction direction, together with the first housing;
• and
• an accessory device detachably attachable to the housing;
• wherein the accessory device comprising
• a main body configured to be mounted to the expanded area of the housing, the main body comprising a mounting surface which is extended along the expansion direction, and
• a coupling unit which detachably attaches the main body to the housing,
• wherein the main body which is attached to the housing which is expanded, disposes the mounting surface to support the expanded area of the display module together with the expanded area of the first housing.