A ventilation member having: a breathable film transmitting gas passing through an opening portion of a housing in a state in which the breathable film is fixed to the opening portion; and a support including a supporting portion for supporting the breathable film and an insertion portion to be inserted into the opening portion of the housing; wherein the insertion portion has a lock portion in an insertion-start-side end portion thereof, the lock portion having a tapered forward end, while the insertion portion is divided into a plurality of parts circumferentially at least on an insertion start side thereof.