To prevent the deterioration in casting property and workability and improve the wear resistance of only a necessary part by constituting a cylinder bore part so that the vicinity of the top dead center thereof is formed of a remelted hyper-eutectic AL-Si alloy metallographic structure.

A lubricating oil film is hardly formed near the top dead center or bottom dead center of a cylinder bore where the speed of a piston reciprocally sliding on the inner surface of the cylinder bore, and higher wear resistance is required in the vicinity of the top dead center. The top dead center vicinity of the cylinder bore is remelted to form hyper-eutectic Al-Si alloy metallographic structure, and in the remelted part, primary crystal Si or eutectic Si are finely and uniformly dispersed by quenching coagulation in the treatment. The body part of a cylinder block is formed of hypo-eutectic Al-Si alloy or eutectic Al-Si alloy to improve the wear resistance without sacrificing the casting property or workability. Such a cylinder block is provided with a continuous integrated structure without requiring a foreign material such as cast iron or ceramics, easy to recycle, inexpensive, and excellent in heat conductivity.