PURPOSE: To promote water resistance and, at the same time, to make it possible to use a composite member for a long period of time by interlocking aluminum templates with synthetic resin bodies fixed to WPC treated members unevenly in one direction, and forming it in the other direction so that it is capable of moving.

CONSTITUTION: Aluminum templates are constituted of a sliding door frame 14, window frame 19, etc., are formed and synthetic resin bodies 6 fixed to WPC treated members 1 and 1 are interlocked with each other unevenly in one direction, and they are so formed that they are capable of moving in the other direction. Antifriction is applied to the contact surface of the aluminum templates 14, 19 with the synthetic resin bodies 6. According to the constitution, the effects of stability of size, prevention of cracking, corrosion resistance, ant resistance, etc., can be exhibited.