A compound represented by Formula (I) or a salt thereof. wherein each of R 1 and R 2 independently represents a hydrogen atom, a substituted or unsubstituted C6-10 aryl group, or a substituted or unsubstituted 3- to 6-membered heterocyclyl group, with the proviso that in the case of R 2 being a hydrogen atom, R 1 is a substituted or unsubstituted C6-10 aryl group, or a substituted or unsubstituted 3- to 6-membered heterocyclyl group, and in the case of R 1 being a hydrogen atom, R 2 is a substituted or unsubstituted C6-10 aryl group, or a substituted or unsubstituted 3- to 6-membered heterocyclyl group, wherein the substituted group on the "C6-10 aryl group" or "3- to 6-membered heterocyclyl group" of R 1 and R 2 is a halogeno group, a C1-6 alkyl group, a C1-6 haloalkyl group, a C1-6 haloalkoxy group, an amino group, a mono C1-6 alkoxy carbonyl amino group, a cyano group, or an oxo group, R 3 represents, a C1-6 alkylsulfonyl group, R 4 represents a C1-6 alkyl group, or a substituted or unsubstituted amino group, wherein the substituted amino group of R 4 is a C1-6 alkyl amino group, a C3-8 cycloalkyl amino group, a C1-6 alkyl carbonylamino group, a mono(C1-6 alkoxy carbonyl) amino group, or a di(C1-6 alkoxy carbonyl) amino group, R 5 represents a hydrogen atom, and Ar represents a substituted or unsubstituted C6-10 aryl group, or a substituted or unsubstituted, 5- to 6-membered heteroaryl group, wherein the substituted group of "C6-10 aryl group" and "5- to 6-membered heteroaryl group" of Ar is a C1-6 haloalkyl group, a C1-6 haloalkoxy group, a C1-6 haloalkylthio group, or a C1-6 haloalkylsulfonyl group. each of R 1 and R 2 independently represents a hydrogen atom, a substituted or unsubstituted C6-10 aryl group, or a substituted or unsubstituted 3- to 6-membered heterocyclyl group, with the proviso that in the case of R 2 being a hydrogen atom, R 1 is a substituted or unsubstituted C6-10 aryl group, or a substituted or unsubstituted 3- to 6-membered heterocyclyl group, and in the case of R 1 being a hydrogen atom, R 2 is a substituted or unsubstituted C6-10 aryl group, or a substituted or unsubstituted 3- to 6-membered heterocyclyl group, wherein the substituted group on the "C6-10 aryl group" or "3- to 6-membered heterocyclyl group" of R 1 and R 2 is a halogeno group, a C1-6 alkyl group, a C1-6 haloalkyl group, a C1-6 haloalkoxy group, an amino group, a mono C1-6 alkoxy carbonyl amino group, a cyano group, or an oxo group, R 3 represents, a C1-6 alkylsulfonyl group, R 4 represents a C1-6 alkyl group, or a substituted or unsubstituted amino group, wherein the substituted amino group of R 4 is a C1-6 alkyl amino group, a C3-8 cycloalkyl amino group, a C1-6 alkyl carbonylamino group, a mono(C1-6 alkoxy carbonyl) amino group, or a di(C1-6 alkoxy carbonyl) amino group, R 5 represents a hydrogen atom, and Ar represents a substituted or unsubstituted C6-10 aryl group, or a substituted or unsubstituted, 5- to 6-membered heteroaryl group, wherein the substituted group of "C6-10 aryl group" and "5- to 6-membered heteroaryl group" of Ar is a C1-6 haloalkyl group, a C1-6 haloalkoxy group, a C1-6 haloalkylthio group, or a C1-6 haloalkylsulfonyl group. <EOS>