The present invention provides a compound represented by formula (I) (in the formula, R1 to R4 each represent a hydrogen atom, an unsubstituted or G1-substituted C1-6 alkyl group or the like, A represents an oxygen atom or the like, Cy represents a C6-10 aryl group or the like), an N-oxide compound thereof, a tautomer or salt thereof. The present invention also provides an agricultural and horticultural fungicide, harmful organism control agent and insecticidal/acaricidal agent containing at least one compound selected from the group consisting of a compound represented by formula (I), a tautomer and salt thereof, as an active ingredient.