An oxidation inhibitor containing, as an active ingredient, an aminocarbonyl compound having a structure resulting from binding of an amino group of a compound having sphingoid base structure and a carbonyl group of a carbonyl compound. The oxidation inhibitor has high oxidation inhibitory effects, and inhibits oxidation of fats and oils, in particular, fats and oils containing a large proportion of polyunsaturated fatty acids to prevent deterioration due to oxidation of fats and oils.
