To provide a marine engine cylinder liner which is made of flake graphitic cast iron and has a wall thickness of 30 mm or more and high strength with tensile strength of 250 MPa or more.

The cylinder liner is made of flake graphitic cast iron which has a composition containing C:2.4 to 3.6%, Si:0.8% or more and less than 2.8%, Mn:1.1 to 3.0%, and further P:0.01 to 0.6% and B:0.001 to 0.2%, or further S:above 0.01% to 0.15% or less, one or more kind selected from among Cu, Cr, Mo, Ni of 0.1 to 6.0% in total, one or more kind selected from among W, V, Nb of 0.01 to 5.0% in total, and one or more kind selected from among Sn:0.3% or less and Sb:0.3% or less, and which has a structure in which 8% or less of carbide is dispersed. This can secure high strength with tensile strength of 250 MPa or more, and can meet the need of high output of a diesel engine.