nitrogen-containing heterocyclic compound represented by the formula (I) or a salt thereof and, fungicide for agricultural and horticultural containing at least one as an active component selected from them. R: OR1, SO2R3 etc. (R1,3: unsubstituted or substituted C1~8 alkyl, etc.) B: nitrogen atom, carbon atom D, E: 5-7 membered hydrocarbon ring, etc. X1,2: halogeno group X: oxygen atom m: 0-5 n: 0-3式(I)で表される含窒素ヘテロ環化合物またはその塩、およびそれらから選ばれる少なくとも1種を有効成分として含有する農園芸用殺菌剤。R:OR1、SO2R3等(R1,3:無置換又は置換C1~8アルキル等)B:窒素原子、炭素原子D,E:5-7員炭化水素環等X1,2:ハロゲノ基等X:酸素原子等m:0-5;n:0-3