To obtain the subject new compound having excellent biocompatibility and suitable for raw material, etc., for an organismic material such as a hybrid artificial organ by ring-opening polymerization of a sugar-substituted α-amino acid-N-carboxy anhydride using an amine compound having styryl group as an initiator.

This new sugar-containing polypeptide macromonomer has a structure of formula I (R is an acetyl or H; R' is a 1-8C alkyl or phenyl; (m) is an integer of 0-100; (n) is an integer of 0-100; X is OR or NHR). The macromonomer is useful as a monomer giving a graft copolymer excellent in biocompatibility, having a sugar-containing polypeptide at a side chain, suitable for an advanced-type organismic material, etc., such as a hybrid artificial organ, an organ simulation or a missile drug by copolymerizing with another vinyl-based monomer. The macromonomer is obtained by ring-opening polymerizion of a sugar-substituted α-amino acid-N-carboxy anhydride of formula III using an amine compound having styryl group of formula II as an initiator.