An object of the present invention is to provide a preventive or therapeutic agent for inflammatory diseases or degenerative intervertebral disk diseases. A coumarin derivative or a pharmaceutically acceptable salt or hydrate thereof which is an active ingredient of the preventive or therapeutic agent of the present invention exhibits an excellent suppressive action in a pharmacological test where production of inflammation-related factor such as inflammatory cytokine or fibrosis-related factor as an index. Moreover, said compound also exhibits an excellent suppressive action to pulmonary fibrosis model animals and degenerative intervertebral disk disease model animals. Accordingly, the present invention is very useful as a preventive or therapeutic agent for inflammatory diseases and degenerative intervertebral disk diseases.