To prevent a crack from being generated on a top clear layer by specifying the hardness difference between the clear layer and a decorative coating film layer on the top of a substrate comprising an inorganic ceramic board and the clear layer formed on the decorative coating film in the decorative board in which an aqueous coating material is applied on the substrate which are cured and film-formed to form the decorative coating layer.

In the cast of producing an inorganic ceramic decorative board, a plate-shaped molding using an inorganic binder and an inorganic or organic reinforcing material as principal starting materials, e.g. a fiber reinforced cement board, a cement board containing wooden chips, a calcium silicate board or a gypsum board is used as a substrate. The top of the substrate is coated with an aqueous coating material and this coating material is hardened to form a decorative coating film. Then, the top of the decorative coating film is coated with a UV-curing clear coating material and this coating material is cured by irradiation with UV to form a clear layer. In this case, the hardness difference between the clear layer and the decorative coating film is adjusted to ≤3H pencil hardness so that a crack is not generated on the clear layer.