PURPOSE: To obtain the cylinder block having high reliability by eliminating an annular excess metal part formed by a molten metal reservoir part after a molten metal is solidified.

CONSTITUTION: The side wall forming surface 11 which is separated and placed against an end face 3a of a cylinder liner 3 and the outside peripheral surface 21a and forms a cavity 15 of a prescribed size against the outside peripheral surface 21a is provided. On the end face forming surface 11, a molten metal reservoir part 13 constituted of an annular recessed part 80 as to face the part being near the outside periphery of the end face 3a and the cavity 15 in the whole periphery of the cylinder liner 3 is provided. By using a casting mold 10 constituted in such a way, and filling a molten metal 16 extending from the cavity 15 to the part of the molten metal reservoir part 13 at the time of pouring a molten metal, an annular excess metal part 17 formed by the molten metal reservoir part 13 after the molten metal 16 is solidified is eliminated. In such a way, by reducing the working manhours and decreasing the loss portion of material, etc., the cost is reduced.