The present invention provides a surface treating agent. The surface treating agent is hydrophobic during the drying process, and slowly becomes hydrophilic after contacting water so as to maintain make up property and washability. The surface treating agent for the first segmented copolymer shown in the general formula (1), wherein R1 and R2, independently stand for alkyl, poly alkylene oxide, acyl, alkyl phenyl and aralkyl X shows that non-adjacent carbon atoms can be replaced by oxygen atoms so as to form alkyl chains with 1-18 carbon numbers for ether Y stands for a single bond or plus 2 linking group Z1 stands for hydrogen atom or methyl and n and m stand for the degree of polymerization.
