To provide a light weight and highly rigid concrete form at low cost by bonding integrally a reinforcing board which expands ribs in the form of lattices on the rear side of a sheathing board, which is made of fiber reinforced thermosetting resin or the like and formed like a flat board by bending the peripheral edge.

The peripheral edge of thermoplastic resin, such as polypropylene of thermosetting resin, such as epoxy resin is bent with plastics reinforced with glass fiber or alamido resin fiber or the like, thereby forming a sheathing board member 2 in the form of a flat board. A reinforcing board 4 which expands reinforcing ribs 3a and 3b like lattices, is separately formed, thereby bonding the sheathing board member 2 with the reinforcing board 4 while the resin is still in a non-cured state and curing and integrating them. In addition, the matrix-formed resin and reinforced resin are properly assembled and used, which makes it possible to confirm a current status of a concrete placement or its quality from outside. This construction makes it possible to provide a concrete form, which is highly rigid and excellent in workability, at light weight and low cost.