The purpose of the invention is to provide a novel coumarin derivative or pharmaceutically acceptable salt thereof and a drug containing this compound as an active ingredient. This coumarin derivative or pharmaceutically acceptable salt thereof presents an excellent cartilage destruction-inhibiting effect and synovial cell proliferation-inhibiting effect in pharmacological studies taking release of sulfated glycosaminoglycans (sGAG) and proliferation of synovial cells as indicators, and therefore is extremely useful as an active ingredient of pharmaceutical compositions for the prevention or treatment of osteoarthritis, rheumatoid arthritis, and other such arthropathies. (In the formula R1 and R2 are the same or different, (a) alkoxy, alkyl, cyano, nitro, hydroxy, trifluoromethyl, amino, carboxy, alkoxycarbonyl, phenyl, or phenyl optionally substituted by one or two halogens, (b) pyridyl, (c) alkyl, or (d) thienyl.)
