PURPOSE: To realize a light weight of a panel, to make the handing easier, and to reduce the transport cost extensively, by composing a concrete front wall and a concrete rear wall incorporated by burying a part of a reinforcing member, on the front and the rear surfaces of a reinforcing member which is made by framing lateral and longitudinal reinforcing bars.

CONSTITUTION: A reinforcing member 2 in a panel 1 is composed by framing a truss reinforcement 21, a main reinforcement 22, a backing reinforcement 23, and horizontal reinforcements 24. Then a metallic molding box 3 suitable to a panel 1 to manufacture is used, metallic boxes 25 to connect panels 1 and 1 are installed to several positions at the end sides of the reinforcing members 2, they are fitted in the molding box 3, and after positioning the reinforcing members 2 in the space of the molding box 3 by supporting the boxes 25, a concrete slurry 10 is poured in the molding box 3. And the rear side of the reinforcing member 2 is fitted in the molding box 3, and the concrete slurry 10 is poured and solidified to complete the panel 1. Consequently, an extensively light weight of the panel 1 can be realized.