An open/close mechanism can be used for paper trays of an image forming apparatus. The open/close mechanism includes a plate member provided on a side of a housing of the image forming apparatus and configured to pivot upon an axis between an open position and a close position, and a box member that is arranged in the housing beneath the plate member and that can be drawn out of the housing from the side. The open/close mechanism includes also includes a restricting unit that is coupled to the plate member and that abuts against the box member when the box member is set in the housing and when the plate member is in the open position thereby restricting detachment of the box member from the housing.