A compound represented by the following formula [I] or a salt acceptable for pharmaceutical use thereof, or a solvate thereof: ** Formula ** where, Ra is (1) a hydrogen atom, or (2) an atom of halogen； Rb is (1) a hydrogen atom, (2) a halogen atom, (3) a C1-6 alkyl group optionally substituted by 1 to 5 identical or different substituents selected from the following group A, (4) a C2 alkenyl group -6 optionally substituted by 1 to 5 same or different substituents selected from the following group C, (5) a C2-6 alkynyl group optionally substituted by 1 to 5 same or different substituents selected from the following group C, (6) a cyano group, (7) -C (>； = O) -Rb1 where Rb1 is a hydrogen atom or a C1-6 alkyl group optionally substituted by 1 to 5 identical or different substituents selected from the following group B, (8) -C (>； = O) -ORb2 where Rb2 is a hydrogen atom or a C1-6 alkyl group optionally substituted by 1 to 5 identical or different substituents selected from the following group B, (9) -C (>； = O) -NRb3Rb4 where Rb3 and Rb4 they are the same or different and each is a hydrogen atom or an optionally substituted C1-6 alkyl group by 1 to 5 identical or different substituents selected from the following group B, (10) -C (>； = O) -NRb5-ORb6 where Rb5 and Rb6 are the same or different and each is a hydrogen atom or a C1-alkyl group 6 optionally substituted by 1 to 5 identical or different substituents selected from the following group B, (11) -ORb7 where Rb7 is a hydrogen atom or a C1-6 alkyl group optionally substituted by 1 to 5 same or different substituents selected from the following group B, (12) -NRb8Rb9 where Rb8 and Rb9 are the same or different and each is a hydrogen atom or a C1-6 alkyl group optionally substituted by 1 to 5 same or different substituents selected from the following group B, (13) - NRb10-C (>； = O) -Rb11 where Rb10 and Rb11 are the same or different and each is a hydrogen atom or a C1-6 alkyl group optionally substituted by
