PROBLEM TO BE SOLVED: To provide ketone derivatives which are highly safe and have phosphodiesterase 4 inhibitory action.SOLUTION: A novel ketone derivative is represented by the specified general formula (1), where A represents pyrazolo[1,5-a]pyridine or imidazo[1,2-a]pyridine, R1 represents a C1-6 alkyl group or the like, R2 represents a C1-6 alkoxy group or the like, R3 represents a hydrogen atom or halogen atom, R4 and R5 are identical or different and each represent a hydrogen atom or halogen atom, R6 represents a C1-6 alkyl group, m represents 0 or 1, and n represents 0 or 1.【課題】ホスホジエステラーゼ４阻害作用を有し、かつ、安全性の高いケトン誘導体の提供。【解決手段】一般式（１）［式中、Ａは、ピラゾロ[1，5‐a]ピリジン又は、イミダゾ[1,2-a]ピリジン、Ｒ１はＣ１－６アルキル基など、Ｒ２はＣ１－６アルコキシ基など、Ｒ３は水素原子又はハロゲン原子、Ｒ４及びＲ５は、同一又は異なって、水素原子又はハロゲン原子、Ｒ６はＣ１－６アルキル基、ｍは０又は１を表し、ｎは０又は１を表すを表す]で表される新規なケトン誘導体。【選択図】なし
