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, R1 represents a carboxyl group or the like； R2 represents a hydrogen atom or the like； R3 represents an optionally substituted aryl group or the like； X1 represents a carbonyl group； X2 represents a bonding hand； X3 represents a bonding hand； X4 represents a bonding hand or the like； and A represents an optionally substituted phenyl group or the like.)
