An object of the present invention is to provide a cassette shutter in which the durability of a curved shutter for opening and closing a medium entrance of a cassette is improved, and assembly of parts is simple. In the present invention for achieving said objective, a cassette shutter, which is slidably disposed on front and bottom surfaces of a cassette storing a paper medium therein and opens and closes an entrance formed in the front surface of the cassette, is configured to include: a plurality of pieces arranged longitudinally and a fastening pin that passes through and thereby fastens a lower portion of an upper-side piece and an upper portion of a lower-side piece so as to enable relative rotation of the plurality of pieces.