One method for lining the inner surface of a steel cylinder with copper alloy is to pour molten copper alloy into a heated cylinder, which has been previously filled with borax anhydride. This process replaces the molten borax anhydride with molten copper alloy. After the cylinder is cooled, the embedded copper alloy is drilled along its center axis so that a prescribed thickness of the copper alloy may remain. However, when the cylinder is made of cast iron including high concentration of carbon, the copper alloy does not bond to the inner surface of the cylinder. To solve this problem, we investigated to utilize the decarburization phenomenon. Two methods were investigated. In one method, the cast iron cylinder filled with FeO powder is heated at a high temperature so that the carbon precipitates in the cast iron may get out through reaction with O2 formed by decomposition of FeO. In the other method, the cast iron cylinder is only heated in air. A decarburized layer is formed beneath an oxide layer. In both methods, the lining of cast iron with copper alloy was attained.