The present invention provides a functionalized polymer which can be used extensively in the field of medical drugs as well as medical devices and which is obtainable in an organic synthetic manner from glycosaminoglycan controlling adhesion, migration and proliferation of cells via linkage to various cellular growth factors or cytokines or direct interactions with the cells. The functionalized polymer of the present invention is characterized in that it comprises a carbohydrate corresponding to at least a part of the basic structure of glycosaminoglycan introduced into a vinyl-type polymer chain.