It is an object of the present invention to provide an agricultural and horticultural fungicide composition that exhibits an excellent control effect on plant diseases even in a small dose and causes no fear of phytotoxicity to useful plants. The agricultural and horticultural fungicide composition of the present invention comprises at least one compound A selected from the group consisting of a compound of formula (1) {wherein each X independently is a halogeno group or a C1-6 alkyl group; n is the number of X and is any integer of 0 to 5; X′ is a halogeno group; R1, R2 and R3 each independently are a C1-6 alkyl group, a C1-6 alkoxy group or a hydroxyl group; and A1 and A2 each independently are a nitrogen atom or a carbon atom}, and the like, and at least one compound B selected from the group consisting of silthiofam, an antibiotic, propineb and chinomethionat.