PURPOSE: To join plastic pipes within a short period readily and tightly that will be used for heating or supplying hot water, by heating one end of the plastic pipe, enlarging the end, cooling the end so that the end is formed into a heat- shrinkable end, then inserting one end of the other plastic pipe into said heat- shrinkable end and heating said heat-shrinkable end to be shrunk.

CONSTITUTION: One end of a plastic pipe (e.g. one having configuration memory such as one made of a crosslinked polyethylene) 2 is heated to or over the softening point of the plastic pipe. Then the end is enlarged diametrically and with the configuration kept the end is cooled to be formed into a heat-shrinkable end 1. Thereafter, one end 4 of the other plastic pipe on which an adhesive (e.g. a hot melt adhesive or the like) 5 has been applied is inserted into the heat- shrinkable end 1 and the heat-shrinkable end 1 is heated to be shrunk thereby joining the plastic pipes.

EFFECT: As a joint is not used, the cost of joining becomes low.