Cylinder liner and engine

A cylinder liner for insert casting used in a cylinder block is provided. The cylinder liner includes an outer circumferential surface having a plurality of projections. Each projection has a constricted shape. A film of a metal material is formed on the outer circumferential surface and the surfaces of the projections. As a result, the cylinder liner ensures sufficient bond strength with the casting material of a cylinder block, and sufficient thermal conductivity with the cylinder block.