The molecular interaction of saccharide is weak in the monovalent state, but the saccharide assembling structure exhibit a stronger molecular interaction based on the amplification effect, which are so-called glycoside-cluster effect. The saccharide clusters showed strong interactions to the lectins and cells. Glycopolymers are the polymer having saccharide side chains, which exhibit strong molecular interaction based on the saccharide clusters structures (Fig. 153.1a) [1]. Glycopolymers are biofunctional polymers and biomaterials with strong molecular recognition ability. The glycopolymers are expected to be applied to the pharmaceuticals such as nanomedicine, drug delivery systems, and scaffold materials for tissue engineering, because of the strong molecular recognition ability. It is also expected the biomaterials for bio-separation materials, biosensors, and molecular tools for detecting proteins and cells. The barriers to practical application include clear analysis of the performance of glycopolymers, molecular stability, and establishment of clear synthesis-manufacturing methods.