A method for producing monovalent unsaturated free fatty acids having 20 and/or 22 carbons or low-grade alcohol esters thereof, said method involving the following: obtaining free fatty acids or low-grade alcohol esters through the hydrolysis or alcoholysis of oils and fats derived from marine products； carrying out distillation on the free fatty acids or low-grade alcohol esters, and reducing the concentration of fatty acids with 18 or less carbons in the low-grade alcohol esters or free fatty acids； and collecting fractions of monovalent unsaturated free fatty acids having 20 and/or 22 carbons or low-grade alcohol esters thereof by column chromatography based on reversed-phase distribution.
