A heterocyclic derivative represented by the general formula [1]: ** Formula ** or its tautomer or a pharmaceutically acceptable salt thereof, wherein ring A is a group represented by the general formulas [2], [3] or [ 4]: ** Formula ** wherein X1 is NH, N-alkyl or O； A1 is hydrogen or alkyl； A2 is i) hydrogen； ii) halogen； iii) alkyl optionally substituted with one to three groups selected from the group consisting of halogen, amino, monolakylamino, dialkylamino, carbamoyl, monoalkylaminocarbonyl, dialkylaminocarbonyl, a saturated cyclic aminocarbonyl, alkoxy, alkoxyalkoxy and alkylcarbonyloxy； iv) cycloalkyl optionally substituted with alkyl optionally substituted with one to three halogens； v) alkoxy； vi) a saturated heterocycle group optionally substituted with alkyl, alkyloxycarbonyl, alkylcarbonyl or oxo； vii) alkylthio； viii) alkylsulfonyl； ix) alkylsulfinyl； x) a group represented by the general formula [5]: ** Formula ** wherein R3 and R4 are the same or different group selected from: a) hydrogen； b) alkyl optionally substituted with a group selected from the group consisting of monoalkylamino, dialkylamino, a saturated cyclic amino optionally substituted with alkyl, a saturated heterocycle group optionally substituted with alkyl, alkoxy, hydroxycarbonyl, hydroxyl, alkyloxycarbonyl, and alkylthio, oc) cycloalkyl ； or xi) a saturated cyclic amino optionally substituted with alkyl, amino, monoalkylamino, dialkylamino, alkoxy or hydroxy； R1 is phenyl, benzyl, naphthyl, cycloalkyl, cycloalkylmethyl, heteroaryl, heteroarylmethyl, 1,2,3,4-tetrahydronaphthalen-5-yl, 1,2,3,4-tetrahydronaphthalen-6-yl, 2,3-dihydro- 1H-inden-4-yl, 2,3-dihydro-1H-inden-5-yl, 1,2-dihydrocyclobutabencen-3-yl, 1,2-dihydrocyclobutabencen-4-yl or alkyl, wherein said phenyl, benzyl , cycloalkyl, cycloalkylmethyl, heteroaryl, and heteroarylmethyl is optionally substituted with one to three groups selected from the group consisting of i) halogen, ii) alkyl optionally substituted with one to t
