Abstract: A seal structure for sealing between a through hole and a conduit located in the through hole. The seal structure includes a conduit located in the through hole and a foaming material. A wire is inserted in the conduit. The foaming material is located between the outer surface of the conduit and the inner surface of the through hole. The foaming material expands when heated and seals the space between the outer surface of the conduit and the inner surface of the through hole. Both ends of the conduit are sealed with a fireproof material between the inner surface of the conduit and the outer surface of the wire.