To obtain a lightweight panel having a high surface strength, a fireproofness and high heat insulating properties by a method wherein an inorganic molded body is laminated on at least one side of a phenolic resin foam panel, the bulk density and a non-interconnecting cell rate of which are respectively specified.

The density of a phenolic resin foam is 10-300 kg/m3, preferably 15-200 kg/m3. If the density exceeds 300 kg/m3, the feature as the lightweight properties lessens and, at the same time, the heat insulating properties become low. If its density is below 10 kg/m3, the mechanical strength such as a compressive strength and the like become small and a resultant panel easily tends to break during its handling. The non-interconnecting cell percent of the phenolic resin foam is 70% or more, preferably 80% or more. If the non-interconnecting cell percent is below 70%, the water absorption properties of the panel become larger and, under the condition that defects such as cracks or the like develop in some part of a laminated inorganic molded body, the phenolic resin foam absorbs water through those defect portions, resulting in developing the possibility for lowering the heat insulating properties of the panel.