A medium cassette includes a slidable cassette pull-out part and is capable of being lengthened and shortened, and a medium tray has a first pull-out part slidably provided to a tray base, the medium tray can be lengthened and shortened, and the medium tray is detachably provided to the top of the medium cassette. The cassette pull-out part is provided with a first engaging protrusion and a second engaging protrusion which engage with the tray base, and inclined surfaces are formed on both sides in the detachment direction of these engaging protrusions. The designs of these inclined surfaces, of the heights of the protrusions, and of other features make it possible to perform the operations of lengthening/shortening and installing/detaching the medium cassette and the medium tray separately from the other component's side without restriction, even while the medium cassette and the medium tray are engaged together.