PURPOSE: To maintain watertightness even after long-term use by embedding electric heating elements in the inner peripheral surface of the end part of a second short pipe, on the side to which a first short pipe is connected in a joint of such constitution that the end parts of a first and a second short pipes made of thermoplastic resin are fittingly inserted in the slidable state.

CONSTITUTION: A sliding pipe joint q made of polyethylene resin is formed of a first short pipe 2 and a second short pipe 3 inserted in the mutually slidable state. Electric heating elements 4, 5 formed of nichrome wire are embedded in the inner peripheral surface of both end parts of the second short pipe 2. In the case of connecting existing thermoplastic resin pipes 6, 7 by this sliding joint, the first short pipe 2 is inserted into the second short pipe 3 to shorten the length, and then inserted between thermoplastic resin pipes 6, 7. The first short pipe 2 is then pulled out of the second short pipe 3, and the spigot 22 of the short pipe 2 is inserted into the socket 61 of the thermoplastic resin pipe 6, while the spigot 71 of the pipe 7 is inserted into the socket 32 of the short pipe 3. Integral connection is terminated by the melting of a connecting part by current application to the heating elements 4, 5, 62.