Provided is a compound having a superior acid secretion suppressive action, antiulcer activity and the like. A compound represented by the formula wherein R1 is a substituent, R2 is (i) a hydrogen atom, (ii) a C1-6 alkyl group optionally having a halogen atom or (iii) a cyano group, R3 is (i) a hydrogen atom, (ii) a halogen atom, (iii) a cyano group, (iv) a C1-6 alkyl group optionally having a halogen atom or (v) a C1-6 alkoxy group optionally having a halogen atom, one of R2 and R3 is a hydrogen atom, and the other is a substituent other than a hydrogen atom, or a salt thereof.
