The present inventors discovered that an HMGB1 fragment peptide having a particular amino acid sequence exhibits effects of inhibiting finger adhesion and digestive tract scarring and prolonging survival in the dystrophic epidermolysis bullosa model mice. Also in the skin ulcer model, administration of the specific HMGB1 fragment peptide was found to inhibit the fibrosing of skin during the healing process of the ulcer. Based on these findings, the present application provides pharmaceutical compositions for the treatment of fibrotic diseases, which comprise the specific HMGB1 fragment peptide.
