A pyridazinone compound of formula (I): ** Formula ** where: R 1 represents hydrogen, a C 1-6 alkyl group, a C 1-6 haloalkyl group, a C 3-8 cycloalkyl group, a C 3-8 halocycloalkyl group, a group (C1-6 alkyl) C3-8 cycloalkyl, a group (C3-8 cycloalkyl) C1-6 alkyl, a group (C3-8 cycloalkyl) C3-8 cycloalkyl, a group (haloC3-8 alkylcycloalkyl) C1- alkyl 6, a group {(C1-6 alkyl) C3-8 cycloalkyl C1-6 alkyl, a group (C1-6 alkoxy) C1-6 alkyl, a group (C3-8 cycloalkoxy) C1-6 alkyl, a group {(C1-6 alkoxy) C1-6 alkoxy} C1-6 alkyl, a group (C1-6 alkylthio) C1-6 alkyl, a group (C1-6 alkylsulfinyl) C1-6 alkyl, a group (C1 alkylsulfonyl -6) C1-6 alkyl, a C1-6 phenylalkyl group optionally substituted with one or more substituents selected from Group A, a C3-6 alkenyl group, a C3-6 alkynyl group, or a tetrahydropyranyl group； R2 represents halogen, a cyano group, a nitro group, a C1-6 alkoxy group, a C1-6 haloalkoxy group, a C1-6 alkylthio group, a C1-6 alkylsulfinyl group, a C1-6 alkylsulfonyl group, a haloalkylthio group C1-6, a C1-6 haloalkyl sulfinyl group, a C1-6 haloalkylsulfonyl group, a C3-8 cycloalkoxy group, a C1-6 alkoxy (cycloalkyl) group, a C1-6 alkyl C1-6 thioalkoxy group, a C1-6 alkoxy group C1-6 alkoxy, a C3-6 alkenyloxy group, a C3-6 alkynyloxy group, a C1-6 cyanoalkoxy group, a group (C1-6 alkoxycarbonyl) C1-6 alkoxy, a C1- carbamoylalkoxy group 6, a group (C1-6 alkylaminocarbonyl) C1-6 alkoxy, a group (C1-6 dialkylaminocarbonyl) C1-6 alkoxy, an amino group, a C1-6 alkylamino group, a di (C1-6 alkyl) amino group, a formylamino group, a (C 1-6 alkyl) carbonylamino group, a C 1-6 hydroxyalkyl group, a (C 1-6 alkoxy) C 1-6 alkyl, a (C 1-6 haloalkoxy) C 1-6 alkyl group, a C3-8 (cycloalkoxy) C1-6 alkyl group, a {(C3-8 cycloalkyl) alkoxy group C1-6} C1-6 alkyl, a group (C1-6 alkylthio) C1-6 alkyl, a group (C1-6 haloalkylthio) C1-6 alkyl, a C1-6 cyanoalkyl group, a C1-6 hydroxyiminoalkyl group , a group (C1-6 alkoxyimino) C1-6 alkyl, a formyl group, or a group (C1-6 alkyl
