PURPOSE: To allow a retaining agent to come throughout decorative bodies and ensure the decorative bodies to be retained on the surface mold by overspreading non-woven fabric on the mold surface of a surface mold, and mounting the decorative bodies on the non-woven fabric.

CONSTITUTION: The surface mold 10 is coated with oil in its mold plate 11. The base plate 11 of the surface mold 10 Is overspread with non-woven fabric 20. Decorative bodies 3 is placed on a predetermined position of the non-woven fabric 20. After that, a fluid resin retaining agent 8 of a liquid rubber or the like is poured in the surface mold 10 to then be cured. The surface mold 10 and end surface mold are advanced to be positioned at the molding position and, by keeping this condition, fluid concrete is poured thereon. While feeding air from an air feeding part 40, the surface mold 10 is withdrawn. In this instance, since air is spouted from an air blowing out port 41, air comes between the non-woven fabric 20 on the mold surface 11a of the surface mold 10 and the retaining agent 8, so that the surface mold 10 can easily be released from the non-woven fabric 20 and retaining agent 8.