PURPOSE: To exactly bond frame materials with uniform electric field intensity for the adhesive portion by inserting a V-shaped elastic electrode material projecting from a power-feeding tool into a space between frame materials formed into the corners for a metal frame assembly and then supplying a power to the electrode material.

CONSTITUTION: Metal frame materials 4 of a U-shaped section are assembled so as to form a space 5 with the same width in the bonded portion of the frame materials 4 in four corner portions in order to form a metal frame assembly. Then, a thermosetting resin adhesive 2 is coated on the upper and lower both surfaces of the frame assembly 1, face materials 3 are laid on the upper and lower both surfaces to form metal frame panel a V-shaped elastic electrode material 7 projecting from a movable power-feeding tool 6 is inserted into the space 5 between the corners of the frame assembly 1, the metal frame panel is put between the upper and lower parallel electrodes 9, and then a high frequency current is supplied from a high frequency power source 10 to harden the adhesive 2.