To provide a cylinder linear which has improved resistance to abrasion and improved consume rate of a lubricant while reducing fear of abrasion of a piston.

The aluminum/silicon alloy for the cylinder liner 6 is composed of silicon of 25%, magnesium of 1.2%, copper of 3.9%, iron, nickel, manganese and zinc and the balance aluminum, and further contains primary silicon crystals 8 and intermetallic phases 9, 10, wherein primary silicon crystals 8 having a particle size of 2-15 μm, an Al2Cu phase having a particle size of 0.1-5.0 μm and an Mg2Si phase having a particle size of 2-10.0 μm are included. The silicon primary crystals 8 and the intermetallic phases 9, 10, which have been buried in the surface, are exposed from the sliding surface 7 of the cylinder liner 6, which surface has been precisely processed, and a plateau areas 11 formed by exposure of the primary crystals 8 or particles in the intermetallic phases 9, 10 are allowed to round their edges and the rounded edges are gradually shifted into an alloy matrix 12.