The present invention provides compounds having 12-lipoxygenase inhibitory effect and medicines inhibiting 12-lipoxygenase selectively, and relates to novel coumarin derivatives and medicines containing the compounds as effective ingredients. Furthermore, this invention relates to compounds capable of converting to compounds inhibiting 12-lipoxygenase activities selectively according to the cleavage of modified moieties in vivo and medicines inhibiting 12-lipoxygenase selectively, and relates to novel coumarin derivatives having acyl groups as modified moieties and medicines containing the compounds as effective ingredients. The compounds of the present invention can inhibit 12-lipoxygenase strongly and selectively, and being useful as medicines for preventing and treating various circulatory diseases such as arteriosclerosis and vasospasm and for preventing of the metastasis of some kinds of cancers, and show low toxicity and few side effects.