To provide a synthetic resin molded article having unprecedented decorative characteristic by finding a new decorating method capable of expressing an iridescent color with a three-dimensional effect smoothly and clearly.

In the method for decorating a synthetic resin molded article, a reflecting surface for reflecting light is arranged in the synthetic resin molded article, a transparent body made of a synthetic resin having an internal strain is arranged on the reflecting surface, and a polarizing film is laminated on the transparent body.