An object of the present invention is to provide aprophylactic or ameliorating agent for pigmentation havinga novel scaffold and an external preparation for skincontaining the same as a component. The object is achievedby providing a prophylactic or ameliorating agent forpigmentation comprising a compound represented by thefollowing general formula (1), an isomer thereof, and/or apharmacologically acceptable salt thereof and an externalpreparation for skin containing the same as a component:(see formula 1)[wherein R1 represents a hydrogen atom or a linear chain orbranched alkyl group having 1 to 8 carbon atom(s)； R2represents a hydrogen atom, a substituted or unsubstitutedaliphatic hydrocarbon group having 1 to 8 carbon atom(s), asubstituted or unsubstituted aromatic group, a substitutedor unsubstituted polycyclic fused aromatic group, or asubstituted or unsubstituted heterocyclic group having a 5to 12 carbon atoms； R3 represents a substituted orunsubstituted aromatic group, a substituted orunsubstituted polycyclic fused aromatic group, or asubstituted or unsubstituted heterocyclic group having a 5to 15 carbon atoms； n represents an integer of 1 or 2； andm represents an integer of 0 to 3.]
