Disclosed is a composition for prophylaxis or treatment of hyperlipidemia, fatty liver, cardiovascular disease or obesity including a compound represented by General Formula I as an effective ingredient: S- (MS)p-(MS)q  General Formula I wherein S represents sialic acid, and (MS)p and (MS)q independently represent a monosaccharide residue.The compound used as the effective ingredient induces body weight loss, decrease of organ fat, decrease of total cholesterol level, increase of HDL-cholesterol level, decrease of LDL-cholesterol level and decrease of leptin, and thereby provides prophylactic or therapeutic activity for hyperlipidemia, fatty liver, cardiovascular disease or obesity. Also, because it has no cytotoxicity or skin side effect, the provided composition may be safely used as a pharmaceutical composition, a neutraceutical composition or a food composition.