Disclosed is a tray assembly. The tray assembly may include a tray having a guide slot, a hinge arm including a cam-shaped portion and rotably coupled to the tray, a cover fixed to an end portion of the hinge arm, a drawer box storable in the tray and having a guide pin at a side portion thereof, the guide pin passing through the guide slot of the tray and being movable along the guide slot by selectively engaging with the cam-shaped portion of the hinge arm.