To eliminate the harmful effect to the electric characteristic and to improve the adhesion between a skin and a metallic layer by forming successively a mold releasing layer, a conductive layer and a metallic layer to a curved-surface forming mold, laminating the prepreg on these layers and removing them from the forming mold after the prepreg is hardened.

A mold releasing layer 2 which undergone a tetrafluoroethylene resin treatment is formed in a curved-face forming mold 1 made of stainless steel. Then a conductive adhesive is applied on the layer 2 by a spray via a silver filler and with no generation of pinholes, so that a conductive layer 3 is formed. The copper is plated on the layer 3 by the electrolytic method for formation of a metallic layer 4. Then the prepreg 5 made of aramide fibers and epoxy resin is laminated on the layer 4 after a chemical adhesion pretreatment is applied to the layer 4. The prepreg 5 is hardened by heating/ pressing via an autoclave after the prepreg 5 is affiliated with the layer 4 by vacuum drawing. Thereafter, a substance 7 including a skin to be the surface of antenna and both layers 4 and 3 is removed from a substance 6 including the layer 2 and the mold 1, and the layer 3 is mechanically or chemically eliminated.