A plastic pipe (10) includes a pipe body (12), and, at an end of the pipe body (12), there is formed a socket which is provided in the inner surface or in the vicinity of the inner surface thereof with a heat generating unit (18). In coupling, an outer peripheral surface of an end of a pipe (28) to be coupled is scraped by a scraper or the like, and the end is inserted into the socket. Then, an electric current is supplied to the heat generating unit (18) such that a heat is generated by the same. Then, synthetic resin of the coupling surfaces of the pipe (28) and the socket and synthetic resin disposed thereabout are fused, so that the both members are fusion-coupled to each other.