Glycosyl amino acids having natural glycan were useful for the interaction assay of oligosaccharides. A glycochip containing the whole structure of an oligosaccharide was easily prepared by the immobilization of the glycosyl amino acid. Furthermore, fluorescence probes were introduced into the glycosyl amino acid while maintaining the whole structure of oligosaccharide. By using these labeled oligosaccharides, fluorescence polarization (FP) and fluorescence correlation spectroscopy (FCS) analyzed the carbohydrate-lectin interaction in a solution assay system.