To enable light thinning with high strength in response to the high output of an engine combining a cylinder liner made of an cast iron having a bainite structure with a piston ring having a hard ceramics coating or a coated layer applied compound chrome plating on its outer periphery surface.

The raw material 2 of a cylinder liner uses a case iron having a bainite structure to improve the strength of the cylinder liner in response to the high output of an engine. This cast iron uses a case iron material having, for example C: 3.2%, Si: 2.1%, Mn: 0.7%, P: 0.2%, S: 0.03%, Cr: 0.3%, B: 0.08%, Cu: 0.4%, a remainder Fe and a pearlite organization consisting of an inevitable impurities and the bainite structure having a high strength with HRC 24∼45 hardness is made by heat treating this cast iron material. While, a hard ceramics coating or the coated layer applied at least one kind of compound chrome plating is given to the outer periphery surface of a piston ring to harden the piston ring 1.