A novel coumarin derivative or a pharmaceutically acceptable salt thereof and also to provide a pharmaceutical agent containing such a compound as an active ingredient is provided. The coumarin derivative or a pharmaceutically acceptable salt thereof exhibits an excellent suppressive action to the destruction of cartilage and suppressive action to the proliferation of synovial cells in a pharmacological test where the release of sulfated glycosaminoglycans (sGAG) and the proliferation of synovial cells are used as indicators whereby it is very useful as an active ingredient of a pharmaceutical composition such as a preventive or therapeutic agent for arthropathy such as osteoarthritis or chronic rheumatoid arthritis.