The present invention provides an agricultural and horticultural fungicidal composition including a compound A which is at least one selected from a nitrogen-containing heterocyclic compound having a specific structure including a compound represented by the formula (1), and a salt thereof, and a compound B which is at least one selected from the group of specific pesticidally active compounds: in the formula (1), X each independently represents a halogeno group or a C1 to 6 alkyl group; n represents the number of X(s) and is an integer of 0 to 6; and X' represents a halogeno group; and R 1 , R 2 and R 3 each independently represent a C1 to 6 alkyl group or a hydroxyl group.