A 1,2,4-triazolone derivative represented by Formula (1A): ** Formula ** R1C represents a C1-C5 alkyl optionally substituted with one to three groups selected from the group consisting of hydroxy, halogen atoms, cyano , C3-C7 cycloalkyl, and C1-C5 alkoxy； C3-C7 cycloalkyl, or saturated 4- to 8-membered heterocycle； R2 represents a hydrogen atom or C1-C5 alkyl； R3 represents aryl or heteroaryl optionally substituted with one or two groups selected from the group consisting of C1-C5 alkoxy, C1-C5 alkyl, halogen atoms, trifluoromethyl, trifluoromethoxy, cyano, hydroxy, difluoromethoxy, and (C1-C5) sulfonyl alkyl ； R4 and R5 may be the same or different and each represents a hydrogen atom, C1-C5 alkyl optionally substituted with one to three groups selected from the group consisting of hydroxy, halogen atoms, cyano, C3-C7 cycloalkyl, and C1 alkoxy - C5； C3-C7 cycloalkyl, or saturated or unsaturated 4 to 8 membered heterocycle containing one or more nitrogen, oxygen, or sulfur atoms in the ring optionally substituted with one or two groups selected from the group consisting of hydroxy, C1-C5 alkyl , C1-C5 alkoxy, halogen, cyano, C2-C5 alkanoyl, and trifluoromethyl； or R4 and R5 optionally, together with the adjacent nitrogen atom, form a saturated or unsaturated 4 to 8 membered heterocycle optionally containing one or more nitrogen, oxygen, or sulfur atoms, in addition to the adjacent nitrogen atom, in the ring optionally substituted with one or two groups selected from the group consisting of hydroxy, C1-C5 alkyl optionally substituted with one or two hydroxy； C1-C5 alkoxy, halogen, cyano, C2-C5 alkanoyl, oxo, aminocarbonyl, mono (C1-C5) aminocarbonyl, dialkyl (C1-C5) aminocarbonyl, trifluoromethyl and amino optionally substituted with one or two groups selected from the group which consists of C1-C5 alkyl and C2-C5 alkanoyl； and the 4 to 8 membered saturated or unsaturated heterocycle optionally has a C1-C5 alkylene group that intersects two different carbon atoms in t
