The present invention relates to a new dihydroxyphenyl compound, and a pharmaceutical composition or a health functional food containing the new dihydroxyphenyl compound having inhibitory activity on Hsp90 or a pharmaceutically acceptable salt thereof. The compound can effectively inhibit Hsp90, and may be useful as a pharmaceutical composition for preventing or treating any one of Hsp90-mediated diseases selected from the group consisting of cancer diseases, degenerative neurological diseases, and viral infections, or a health functional food for prevention or alleviation of such diseases.