An object of the present invention is to provide a method for more strongly preventing oxidation of unsaturated fatty acids using a simple method. In particular, an object of the present invention is to provide a method for suppressing both an unpleasant odor that appears in an initial stage of storage and an unpleasant odor that appears subsequently. The present invention has been accomplished by finding that an unpleasant odor that appears in an initial stage of storage, as well as an unpleasant odor that appears subsequently, can both be suppressed in an unsaturated-fatty-acid-containing water-in-oil composition comprising an aqueous phase A having a pH adjusted to 3.1 to 8 in which at least one member selected from the group consisting of ascorbic acid and polyphenols is dissolved, an aqueous phase B having a pH adjusted to 0.5 to 3 in which at least one member selected from the group consisting of ascorbic acid and polyphenols is dissolved, and an oil phase containing an unsaturated fatty acid, the aqueous phase A and the aqueous phase B, each having a particle size of 500 nm or less, being finely dispersed individually in the oil phase.