A placement plate for placing a recording sheet is provided in a case to be movable upward and downward. A regulating member is supported by the case to be slidable in the width direction of the recording sheet. A locking section is provided on at least one of the placement plate and the regulating member so as to lock the placement plate with respect to the regulating member when the regulating member is located in an area different from an area between the maximum size and the minimum size at the edge of the recording sheet in the width direction.