Provided are a pyridone compound represented by Formula (1):whereinR1 represents a C1-C6 alkyl group which may be substituted, etc.,R2 represents a halogen atom, a cyano group, etc.,R3 and R4 are independent to each other, and each represents a hydrogen atom, a C1-C6 alkyl group which may be substituted, etc., or in combination with the nitrogen atom to which they are bonded form a pyrrolidinyl group, a piperidinyl group, etc., which may be substituted,Y represents a phenyl group which may be substituted, etc.,X represents an oxygen atom or a sulfur atom,and an agricultural and horticultural fungicide containing the same as an active ingredient.
