To provide a method for producing a cylinder block, in the case a cylinder liner is cast-formed, which can stably prevent the intrusion of a molten metal into a space between with a bore pin.

A cylinder block is cast by flowing a molten metal in the space of molds as molds for casting the cylinder block of an engine, i.e., between a movable die 10 in which a cylinder liner 12 is mounted on a bore pin 11, and a fixed mold 20 having a journal space forming part 21 projectingly provided so as to have a part having a width narrower than the outside diameter of the cylinder liner 12. At this time, in a form where the part having a width narrower than the outside diameter of the cylinder liner 12 in the journal space forming part 21 formed at the fixed mold 20 is filled, a mold piece 30 as a separate body abutted against a part of the edge face of the cylinder liner 12 is engaged with the journal space forming part 21, and, the molten metal is made to flow in a state where the movable mold 10 mounted with the cylinder liner 12 is combined with the fixed mold 20 engaged with the mold piece 30.