An external skin care preparation comprising a compound represented by the following general formula (I) or (II), or a salt thereof: ##STR1## wherein R.sup.1 means an aliphatic hydrocarbon group having 9-25 carbon atoms, A and B denote specific groups respectively, R.sup.6 and R.sup.7 are individually an aliphatic hydrocarbon group having 10-26 carbon atoms, and R.sup.8 denotes a group --CH.sub.2 CH.sub.2 OH, --CH.sub.2 COOH or --COCH.sub.3.