In casting metals for dental prosthetic use, superior dental castings free from shrinkage cavities can be obtained by delaying the cooling and solidification of molten metal in mold members such as a sprue, runner and gate and, if necessary, a molten metal reservoir into which the molten metal is poured. Such delay in cooling and solidification can be achieved either by forming the sprue and the like from a heat resisting ceramic tubular body or by further forming a heat insulating layer on the outer periphery of the tubular body.