An N-acyl anthranilic acid derivative represented by general formula (1) or a salt thereof is useful for prevention or treatment of diseases associated with excessive production of collagen. (In the formula, R 1 represents a carboxyl group or the like； R 2 represents a hydrogen atom or the like； R 3 represents an optionally substituted aryl group or the like； X 1 represents a carbonyl group； X 2 represents a bonding hand； X 3 represents a bonding hand； X 4 represents a bonding hand or the like； and A represents an optionally substituted phenyl group or the like.)
