PROBLEM TO BE SOLVED: To provide a pyridine compound or a salt thereof excellent in insecticidal activity and/or acaricidal activity and in safety, and capable of being industrially advantageously synthesized, and a pest-controlling agent, an insecticide or acaricide, and an ectoparasite controlling agent, which contain this as an active ingredient.SOLUTION: A pyridine compound represented by the formula (I) or a salt thereof is provided.【課題】殺虫活性および／または殺ダニ活性に優れ、安全性に優れ、且つ工業的に有利に合成できるピリジン化合物またはその塩、ならびにこれを有効成分として含有する有害生物防除剤、殺虫剤または殺ダニ剤、および外部寄生虫防除剤を提供する。【解決手段】式（I）で表されるピリジン化合物またはその塩【選択図】なし
