<；P>；PROBLEM TO BE SOLVED: To provide a stabilizing agent that is free from a risk of causing infection with a pathogen or transmission of a pathogenic factor, is highly safe and effectively stabilizes peptides exhibiting physiological activities or pharmacological activities, and a peptide composition in which peptides are effectively stabilized. <；P>；SOLUTION: The stabilizing agent is one for stabilizing peptides exhibiting physiological activities or pharmacological activities and is constituted of a synthetic polypeptide having at least an amino acid sequence represented by the formula: Pro-Y-Gly (wherein Y is Pro or Hyp). The synthetic polypeptide may have a collagen-like structure. The molecular weight of the synthetic polypeptide may have a peak within the range of 3×；10<；SP>；4<；/SP>；to 500×；10<；SP>；4<；/SP>；. <；P>；COPYRIGHT: (C)2007,JPO&INPIT
