A printer including a main body and a sheet-supply cassette attachable to and detachable from the main body. The sheet-supply cassette includes a sheet guide movable to a position that depends on size of sheets in the cassette, cam abutment portion that moves integrally with the sheet guide, a cam that moves away from the cam abutment portion when the cassette is detached from the main body, and a detected portion that moves in a linked manner with the cam. The main body includes a cam mover that, when the sheet-supply cassette is attached to the main body, moves the cam until the cam surface of the cam abuts the cam abutment portion and a detection portion that detects the detected portion moved in a linked manner with the cam. The cam surface has a shape that varies movement amount of the cam into abutment with the abutment portion by the cam mover in accordance with the position of the sheet guide.