A loading mechanism includes a frame and a tray on which an information recording medium is placeable. The tray includes a groove part and is movable between a first position where the information recording medium is contained completely inside the frame and a second position where the information recording medium is exposed completely outside the frame. The loading mechanism further includes at least three projections arranged on the frame at predetermined intervals along the sliding directions of the tray. The projections include first and second guide and support parts forming the first and second ends of the arrangement of the projections. The first and second guide and support parts come into substantially point or linear contact with the groove part of the tray so as to guide and support the tray when the tray is in the second position.