The present invention relates to 1,2,3-thiadiazole compounds represented by formula (I): wherein R 1 , R 2 , R 3 , R 4 and R 5 each represents H, halogen, CN, alkyl, alkoxyalkyl, aryl, arylalkyl, alkylcarbonyl or the like； R 6 represents -C=(W 1 )YR 7 in which R 7 reresents H, alkyl, alkenyl, phenylcarbonyl, heterocyclic ring-carbonyl, arylsulfonyl or the like； Y represents O, S, -N(R 11 ), -N(R 11 )O- in which R 11 represents H, alkyl, cycloalkyl, substituted phenyl, or the like； W 1 represents O or S； and symbols in the formula are defined in detail in the specification or salts thereof, and to a plant disease control agent for agricultural and horticultural use which contains the compound as an active ingredient.【解決手段】；如下式(I)1,2,3-噻二唑衍生物或其鹽類：；(I)；{式中R1、R2、R3、R4及R5為H；鹵素；CN；烷基；羰氧烷基；芳基；芳烷基；烷羰基等。R6為-C(=W1)YR7(式中R7為H；烷基；烯基；苯羰基；雜環羰基；芳磺醯基等，Y為O；S；-N(R11)-；-N(R11)O-(式中R11為H、烷基、環烷基、取代苯基等)等，W1為O；S)，及以該化合物為有效成分之農園藝用植物病害防除劑。；【效果】不但對於對象植物具有優異安全性及優異防除效果，且具有極長期間殘效性之優異農園藝用植物病害防除劑。
