PURPOSE: To manufacture a composite panel for construction of outstanding expansion curability, flame resistance, thermal insulation, etc., by carrying out bonding between a hard base and a thermal insulation board both having rough surfaces by application of an adhesive capable of forming an expansion-cured layer containing an inorganic powder.

CONSTITUTION: The decorative surface of a hard base 1 such as a metal plate, etc. is provided with a pattern by embossing, etc. Subsequently, an adhesive 9 such as of polyurethane, containing a blowing agent like trichloroflouromethane incorporated with an aliminum hydroxide powder, etc., and if required, other inorganic aggregates, is applied to the back of said decorative surface by spraying, etc. At the point of creamy gel formation, a bulky thermal insulation board 7 is packed, followed by conveying the resulting composite with keeping the upper and lower surfaces pressed by rollers R1 and R2, respectively for a certain time, carrying out expausion, e.g., through a heating zone, to effect firm bonding between the base 1 and the board 7, thus obtaining the objective composite panel.