An oil/fat composition comprising 5 to 99.9 wt. % of a monoglyccride having, as fatty acid constituents thereof, 15 to 90 wt % of an .omega. 3-unsaturated fatty acid having less than 20 carbon atoms, 1 to 80 wt. % of an .omega. 9-unsaturated fatty acid and 2 to 50 wt. % of an .omega. 9-unsaturated fatty acid; and 0.1 to 49.9 wt. % of a diglyceride, wherein a weight ratio of the diglyceride to the monoglyceride is less than 1 and the content of a polyunsaturated fatty acid having at least 4 carbon-to-carbon double bonds is 20% or less in all the fatty acid constituents. The oil/fat composition according to the present invention has excellent processing properties, good taste and excellent lowering action against glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) levels in blood. It is useful not only for pharmaceuticals but also for preventive or remedial foods of feeds effective for hepatic function disturbances or obesity.