A wire harness includes a plurality of cables arranged in parallel, and a connector including a housing to which end portions of the plurality of cables are connected. Air-tightness between an air-tight block and the cables is maintained by inserting a melting member into cable insertion holes through a first insertion part, vibrating the melting member and pressing the melting member against a first press receiving part formed at an inner wall surface of the cable insertion holes such that a front end portion of the melting member in contact with the first press receiving part is melted into a melt resin to allow the melt resin to be poured into a gap between the cables and the air-tight block and a periphery of the cables to be covered with the melt resin.