Disclosed is a novel aromatic ester compound represented by the general formula ##STR1## in which Pn is a 1,4-phenylene group, R.sup.1 is an alkyl group having 1 to 4 carbon atoms, R.sup.2 is a group selected from the group consisting of perfluoroalkyl groups having 1 to 4 carbon atoms, cyano group, nitro group, 2,2-dicyanoethenyl group and methylsulfonyl group and the subscript n is a number of 2, 3 or 4. These aromatic ester compounds are useful as a second-order non-linear optical material in the ultraviolet wavelength range so that a resin film containing the compound has a good second-order non-linear optical coefficient d.sub.33 of 2-4.times.10.sup.-9 esu.