PURPOSE: To provide a mold structure improved to facilitate the preparation of a liner and be advantageous to modification of the liner configuration and improvement in cooling efficiency, by a method wherein the liner which is assembled from blocks preliminary worked as prescribed forms, is supported in the mold.

CONSTITUTION: A plurality of constituent blocks 12, 12..., which are machined into predetermined shapes from metal blocks with respective sizes, are set at given positions on a metal frame member 11, respectively. These blocks are secured to the frame member 11 by means of bolts 13, respectively, to form a liner 14 having a predetermined configuration of a part of a product. A product part forming surface 16 of the liner 14 is subjected to finishing to provide the surface with a predetermined configuration. Each constituent block 12 is provided with a longitudinal cooling water hole 15, thereby to increase the degree of freedom to form a cooling circuit for the mold and improve the cooling efficiency of the mold.