In an air passage switching door, a packing material having a size approximately corresponding to a plate surface of a door base member is used, and the door base member is crossed with the packing material at a portion around a rotation shaft for rotating the door base member, so that both plate portions of the door base member are bonded to opposite surfaces of the packing material at different areas of the packing material. Accordingly, the air passage switching door can be manufactured using the single packing material in low cost, while having a reduced thickness.