The present invention relates to a dermatologic preparation containing a diamide derivative represented by the following formula (1): ##STR00001## (wherein, R.sup.1 represents a linear or branched hydrocarbon group having 1 to 22 carbon atoms which may be substituted by one or more hydroxy and/or alkoxy groups, R.sup.2 represents a linear or branched divalent hydrocarbon group having 1 to 12 carbon atoms, and R.sup.3 represents a linear or branched divalent hydrocarbon group having 1 to 42 carbon atoms). This diamide derivative (1) is capable of fundamentally improving the water retention capacity and barrier functions of the horny layer, is excellent in miscibility and mixing stability and can be prepared efficiently at a low cost.