A pharmaceutical composition for preventing or treating liver disease is provided. The pharmaceutical composition comprising a compound represented by formula 1 below or a pharmaceutically acceptable salt of the compound as an active ingredient: where A is S, R is a linear or branched C1-C5 alkyl which is non-substituted or is independently or selectively substituted with one or more C6-C10 aryl groups, a benzyl which is non-substituted or is independently or selectively substituted with halogen or one or more linear or branched C1-C4 alkoxy groups, or a hydroxycarbonyl-substituted benzyl, and Y is H or a halogen atom.