Provided are: an agricultural and horticultural fungicide composition which comprises prumycin and a surfactin as active ingredients; and a plant disease controlling method. As the surfactin, surfactin and [Ile7] surfactin are preferred. Also provided is a practically useful agricultural and horticultural fungicide composition having a high efficacy and excellent storage stability, said agricultural and horticultural fungicide composition further comprising calcium chloride so as to remarkably improve the storage stability thereof.