To provide a construction panel which is excellent in water resistance and moisture resistance, improved in cutting performance and excellent in on-site workability, and to provide a floor structural body, a wall structural body, a door structural body and a roof structural body.

The construction panel 1 comprises an inner layer 10, a first outer layer 11 and a second outer layer 12. The first outer layer 11 and the second outer layer 12 are formed by using, as base materials, wood powder and a resin material mainly composed of a thermoplastic resin material. The inner layer 10 is formed by using, as base materials, the wood powder which is compounded at a ratio higher than the compounding ratio of the wood powder in the first outer layer 11 and the second outer layer 12, and the resin material which is compounded at a ratio lower than the compounding ratio of the resin material in the first outer layer 11 and the second outer layer 12 and is mainly composed of the thermoplastic resin material.