[Object] The present invention provides an oil composition in which oxidation of oil is inhibited and a method of inhibiting oxidation of oil.[Solving Means] Provided is an oil composition containing oil, an ionic surfactant, and a polyhydric alcohol, in which a value L2-L1 calculated by the following method is positive. Value L1: a value of lightness of the oil composition Value L2: a value of lightness of an emulsified product obtained by adding 100 mass times of fresh water to the oil composition