PURPOSE: To produce easily a composite casting mold and to form a material layer for an inside surface to a desired thickness in a process for production of a composite casting mold united with a material having low heat conductivity on the inside surface of the casting mold made of a copper-base metal.

CONSTITUTION: A cylinder 2 made of a stainless steel, Ni alloy, etc. having an outside diameter smaller than the inside diameter of a copper or copper alloy cylinder is inserted into said cylinder. The top and bottom ends of both cylinders are hermetically sealed by welding or brazing and are then sealed into a high-pressure vessel 3 where both cylinders are treated at and under a high temp. and pressure of 600W1,000°C and 100W2,000kg/cm2 to join the metals of said cylinders to each other in a solid phase. The welded or brazed parts at both ends are thereafter removed by machining and the intended casting mold is obtd. The casting mold may be also formed by reducing further the thickness thereof by extruding, drawing, etc. then machining both ends.