A conveying roller has a rotary shaft portion, a roller supporting member, and a roller member. The rotary shaft portion is extendable/contractible. The roller supporting member has an interior space. The roller member is supported on the outer circumferential surface of the roller supporting member. The rotary shaft portion includes first and second shafts. The first shaft has one end part inserted into the interior space, and is movable axially relative to a first side surface. The first shaft has a regulating portion displaceable between a permitting position where the regulating portion permits the movement of the first shaft in the insertion direction relative to the roller supporting member without interfering with a rim of an opening and a restricting position where the regulating portion restricts the movement of the first shaft in the insertion direction relative to the roller supporting member by interfering with the rim.