The present invention relates to a composition for preventing or treating hypertrophic scar or keloid, comprising as an active ingredient a compound represented by the following general formula I:S-(MS)p-(MS)q (I)wherein S represents sialic acid, and (MS)p and (MS)q independently represent a monosaccharide residue.The composition of the present invention inhibits proliferation of keloid fibroblasts and induces apoptosis of keloid fibroblasts, thereby effectively preventing or treating keloid. The active ingredient used in this invention is a natural compound or its derivative or isomer and therefore very safe to human.
