A housing (10) is provided with an opening (11) which has a tapered face (12). A ventilation member (2) attached to the opening (11) includes a support (3) having an air passage (30), a waterproof ventilation film (4), and a cover (5). The support (3) has a base (31) to which the waterproof ventilation film (4) is joined, and a shaft (32) that projects from the base (31) and engages with the internal surface of the housing (10). The shaft (32) is equipped with a seal member (6). The seal member (6) is pressed against the tapered face (12) within the opening (11) by a pressing unit (34).