PURPOSE: To produce a clad ingot without generation of defective adhesion, exfoliation, crack, etc. by supporting a core material in a casting mold in such a way that the surface of the core material to be joined to a cladding metal inclines upward then pouring a molten metal into the mold and subjecting the core material to insert casting.

CONSTITUTION: The core material 3 is supported not perpendicularly but inclinedly relative to a molding board 2 in the casting mold 1 in the board 2. Said material is supported and disposed in such a way that the surface of the material 3 to be joined to the cladding metal inclines upward. The molten metal consising of the component different from the component of the material 3 is poured into the remaining casting space in the mold 1 to insert-cast the material 3. The floating of inclusions to near the surface of the material 3 to be joined to the cladding metal is thus accelerated and the accumulation thereof is considrably suppressed. The clad ingot from which a clad plate having no defective adhesion, exfoliation, crack, etc. can be manufactured in obtd. The preferable angle θ of inclination of the inclinedly held material 3 with the line perpendicular to the board 2 is about 5W15°.