PURPOSE: To hold metallic luster in a long period by equipping both a metallic film film layer joined through a binding resin layer and a transparent coating resin layer joined without exposing the whole metallic thin film layer in the lengthwise direction on the surface of a flat bandlike mandrel.

CONSTITUTION: In a first joining stage, a heated and activated three-layer sheet 6 is superposed and contact-bonded in the lengthwise direction on the surface of a flat bandlike mandrel 2. Thereby a joining resin layer 3 is joined surely and excellently to the surface of the mandrel in a state wherein the surface of a metallic thin film layer 4 of the said sheet 6 is protected by a peeling film 5 forming the outer layer of the sheet 6. Then in a peeling stage, only the peeling film 5 is peeled which forms the outer layer in the sheet 6 superposed on the surface of the mandrel 2. Thereafter in a second joining stage, a heated and activated two-layer sheet 9 is superposed and contact-bonded in the lengthwise direction on the surface of the mandrel 2. At this time, the surface of a transparent coating resin layer 7 forming the lower layer of the sheet 9 is protected by a protective peeling film 8 forming the upper layer thereof. In a bending stage, an integrated laminated body 10 is bent and worked into a prescribed cross-sectional shape by a roll bender 21.