A compound represented by formula, or a pharmaceutically acceptable salt, solvate or hydrate thereof,: wherein Ar represents a phenyl group, pyridyl group, thiazolyl group, benzofuranyl group, dihydrobenzofuranyl group, naphthalenyl group, imidazolyl group or pyrazolyl group which may be independently substituted with one, two or three halogens, formyl groups, cyano groups, nitro groups, amino groups, hydroxyl groups or carboxyl groups; or with one, two or three (C1-C6) alkyl groups, (C2-C6) alkenyl groups, (C1-C6) alkylcarbonyl groups, (C1-C6) alkylamino groups, (C1-C6) alkylcarbonylaminocarbonyl groups, (C3-C6) cycloalkylamino groups, (C1-C7) alkoxycarbonylamino groups, di[(C1-C6) alkyl]amino groups, (C1-C6) alkylcarbonylamino groups, (C3-C6) cycloalkylcarbonylamino groups, di[(C1-C6) alkyl]aminocarbonylamino groups, di[(C1-C6) alkyl]aminothiocarbonylamino groups, heteroarylcarbonylamino groups, phenyloxycarbonylamino groups, phenylcarbonylamino groups, (C1-C6) alkylsulfonylamino groups, di[(C1-C6) alkyl]aminosulfonylamino groups, (C1-C6) alkoxy groups, (C1-C6) alkylthio groups, (C1-C6) alkylenedioxy groups, (C1-C6) alkoxycarbonyl groups, amino(C1-C6) alkylcarbonylamino groups, phenyl(C2-C6) alkenylcarbonylamino groups, (C1-C6) alkoxy(C1-C6) alkylcarbonylamino groups, (C1-C6) alkoxycarbonylamino(C1-C6) alkylcarbonylamino groups, phenyl groups or phenyl(C1-C6) alkoxy groups which may be substituted with a halogen, cyano group, amino group, hydroxyl group or carboxyl group; Y represents a (C1-C6) alkylene group which may comprise a carbonyl group in the carbon chain and/or may be substituted with one or two of Ar; R 1 represents a (C1-C6) alkyl group or (C2-C6) alkenyl group; or an amino group substituted with one or two (C1-C6) alkyl groups, (C1-C6) alkoxy groups, (C1-C6) alkoxy(C1-C6) alkyl groups, (C3-C6) cycloalkyl groups or (C2-C6) alkenyl groups; or a (C1-C6) alkylcarbonylamino group which may be substituted with one or two (C1-C6) alkyl groups, (C1-C6) alkoxy groups, (C1-C6) alkoxy(C1-C6) alkyl groups, (C3-C6) cycloalkyl groups or (C2-C6) alkenyl groups; or a heterocyclic group which may be substituted with one or two nitroso groups, formyl groups, hydroxyl groups, (C1-C6) alkyl groups, (C1-C6) alkylcarbonyl groups, (C1-C6) alkoxy groups, (C1-C6) alkoxycarbonyl groups or hydroxy (C1-C6) alkylamino groups; or a phenyl group substituted with a halogen, formyl group, cyano group, nitro group, amino group, hydroxyl group, (C3-C6) or carboxyl group, R 2 represents H; or a (C1-C6) alkyl group, (C2-C6) alkenyl group, (C2-C6) alkynyl group or (C3-C6) cycloalkyl group which may be substituted with one or two halogens, nitro groups or amino groups; and R 3 represents a (C1-C6) alkyl group, (C2-C6) alkenyl group, (C2-C6) alkynyl group, (C3-C6) cycloalkyl group, (C3-C6) cycloalkyl(C1-C6) alkyl group, amino(C1-C6) alkyl group, three- to five-membered ether-(Cl-C6) alkyl group or (C1-C6) alkylcarbonylamino(C1-C6) alkyl group which may be substituted with a halogen or hydroxyl group. Y represents a (C1-C6) alkylene group which may comprise a carbonyl group in the carbon chain and/or may be substituted with one or two of Ar; R 1 represents a (C1-C6) alkyl group or (C2-C6) alkenyl group; or an amino group substituted with one or two (C1-C6) alkyl groups, (C1-C6) alkoxy groups, (C1-C6) alkoxy(C1-C6) alkyl groups, (C3-C6) cycloalkyl groups or (C2-C6) alkenyl groups; or a (C1-C6) alkylcarbonylamino group which may be substituted with one or two (C1-C6) alkyl groups, (C1-C6) alkoxy groups, (C1-C6) alkoxy(C1-C6) alkyl groups, (C3-C6) cycloalkyl groups or (C2-C6) alkenyl groups; or a heterocyclic group which may be substituted with one or two nitroso groups, formyl groups, hydroxyl groups, (C1-C6) alkyl groups, (C1-C6) alkylcarbonyl groups, (C1-C6) alkoxy groups, (C1-C6) alkoxycarbonyl groups or hydroxy (C1-C6) alkylamino groups; or a phenyl group substituted with a halogen, formyl group, cyano group, nitro group, amino group, hydroxyl group, (C3-C6) or carboxyl group, R 2 represents H; or a (C1-C6) alkyl group, (C2-C6) alkenyl group, (C2-C6) alkynyl group or (C3-C6) cycloalkyl group which may be substituted with one or two halogens, nitro groups or amino groups; and R 3 represents a (C1-C6) alkyl group, (C2-C6) alkenyl group, (C2-C6) alkynyl group, (C3-C6) cycloalkyl group, (C3-C6) cycloalkyl(C1-C6) alkyl group, amino(C1-C6) alkyl group, three- to five-membered ether-(Cl-C6) alkyl group or (C1-C6) alkylcarbonylamino(C1-C6) alkyl group which may be substituted with a halogen or hydroxyl group.