Disclosed is a novel compound having HSP90 inhibitory activity or a pharmaceutically acceptable salt thereof, and a medicinal use thereof, and composition comprising a dihydroxyphenyl compound or a benzamide compound, which is a novel compound having the HSP90 inhibitory activity of the present invention can effectively inhibit HSP90, and thus can be usefully used as a pharmaceutical composition for preventing or treating HSP90-mediated diseases or a health functional food for preventing or improving HSP90-mediated diseases, which selected from the group consisting of cancer diseases, degenerative neurological diseases and viral infections.