To further reduce the manufacturing cost of a cylinder block.

In a mold heating step, a dummy liner 7 made of aluminum alloy is used instead of an iron cylinder liner 5 and the dummy liner 7 which is axially longer than the iron cylinder liner 5 is clamped in a state of being sandwiched between a movable mold 1 and a stationary mold 2. This enables the mold to be sealed at both axial end faces 7a and 7b of the dummy liner 7 so that molten metal is prevented from flowing between a liner support 4 and the dummy liner 7, thereby eliminating the necessity of machining the inner circumferential face of the dummy liner 7 and reducing the manufacturing cost of the cylinder block. Since the material of the dummy liner 7 is aluminum alloy which is the same as the molten metal, the dummy cylinder block cast in the mold heating step can be reprocessed efficiently.