PURPOSE: To dispense with cloth cutting work attended with difficulties and to obtain a good finish state by heating the metal wire material inserted in the annular groove part surrounding the three-dimensional curved surface of a work by high frequency dielectric heating when cloth is pushed in said groove part and heating the cloth in the groove part by the metal wire material to cut the same.

CONSTITUTION: Cloth 2 is pressed to the entire surface of a three-dimensional curved surface 11 by the pressing surface 201 of a lower mold 200 to be bonded thereto and, at the same time, a cushion material 300 is sunk and the lower mold 200 falls with respect to a plug 400. With this operation, the circumference of the part bonded to the three-dimensional curved surface 11 of the cloth 2 is pushed in the annular groove part 12 of a work 1 by the metal wire material 500 provided to the leading end of the plug 400 to bond the cloth 2 to the groove part 12. When the metal wire material 500 is subjected to high frequency dielectric heating, the cloth 2 pushed in the groove part 12 to be bonded thereto is burnt off in the groove part 12 or fused to cut off an excessive part 21. By this method, cutting work becomes unnecessary and a good finish state is always obtained.