A method for treating a disease in which Rho kinase is involved. The method is carried out by administering to a patient in need thereof a pharmaceutically effective amount of a compound of the following formula or a pharmaceutically acceptable salt thereof: wherein the ring X is a benzene ring or a pyridine ring; R1 and R2 are hydrogen or alkyl or together form a cycloalkene ring; R3 is hydrogen, substituted alkyl, unsubstituted alkenyl, carboxyl or an ester or an amide thereof, amino or a cyano; R4 is hydrogen, hydroxyl, substituted or unsubstituted alkoxy, unsubstituted alkenyloxy, unsubstituted cycloalkyloxy substituted or unsubstituted alkyl, unsubstituted alkenyl, unsubstituted cycloalkyl, amino, substituted or unsubstituted alkylamino, nitro, cyano or a monocyclic heterocycle; and R5 is a halogen atom or a hydrogen atom.