This invention provides a compound having a high whitening effect and excellent safety and stability, and an external preparation for skin containing the compound. The compound of this invention is a 4-alkylresorcinol derivate represented by the following formula (1) or a salt thereof.(wherein R1 is a branched or cyclic alkyl group having a carbon number of 3~7, or a linear alkyl group having a carbon number of 2~5 R2 and R3 are respectively independently hydrogen atom or a group represented by -P(O)(OR4)(OR5), provided that one or both of R2 and R3 is the group represented by -P(O)(OR4)(OR5) R4 and R5 are respectively independently hydrogen atom or a linear or branched alkyl group having a carbon number of 2~5.)本發明提供一種具有高美白效果,且安全性及安定性亦優異之化合物,以及調配有該化合物之皮膚外用劑。本發明之化合物,係下述通式(1)所示之4-烷基間苯二酚衍生物或其鹽。(式中,R1係分枝或環狀之碳數3至7的烷基,或直鏈之碳數2至5的烷基;R2及R3係分別獨立的氫原子或以-P(O)(OR4)(OR5)所示之基,而R2及R3之其中一者或兩者係以-P(O)(OR4)(OR5)所示之基;R4及R5係分別獨立地為氫原子、或者直鏈或分枝之碳數2至5的烷基)。
