PURPOSE: To obtain an agricultural and horticultural fungicidal composition having extremely highly controlling effects on disease damage of plants than single separate use of each component, showing both preventing effect and treating effect by blending a benzothiazole derivative with a well-known fungicidal compound.

CONSTITUTION: This agricultural and horticultural fungicidal composition comprises (A) at least one of benzothiazole derivatives of the formula (R1 is a lower alkyl, an alkenyl, an alkynyl, a cycloalkyl, an alkoxyalkyl, benzyl, a CO-containing alkyl or a CO-containing alkoxyalkyl; R2 is a lower alkyl, an alkoxy or a 1-3C alkyl containing 1-6 fluorine atoms) and (B) at least one ionic compound among compounds having fungicidal effects, preferably a thiazole-based compound (e.g. hexaconazole), a pyrimidine.piperazine.piperidine.pyridine-based compound (e.g. fenarimol), a morpholine-based compound (e.g. tridemorph), an organic phosphorous compound (e.g. pyrazophos), a quinoxaline-based compound (e.g. quinothionate), a benzimidazole-based compound (e.g. benomyl) and an acrylic acid-based compound as active ingredients.