The present invention is made for the purpose of improving beef quality and upgrading its fat marbling standard (which is called beef marbling standard, or BMS). The fat marbling state is generally called "Shimofuri" in Japanese. This purpose is achieved by vitamin C administration (L-ascorbic acid) to the cattle. The vitamin C can be administered by injection etc., but the easiest way is by oral administration. When only the vitamin C is administered orally, however, it is decomposed by microorganisms in the rumen and the desired effect cannot be obtained. For that reason, the vitamin C needs to be coated with something so that it can be absorbed by the intestinal tract after passing through the stomach. Soybean-hydrogenated oil and fat is desirable for such covering material. An appropriate daily dose of the vitamin C is approximately 20 mg to 60 mg/kg of weight. According to the result of tests conducted on the Japanese Black Cattle, in terms of the yield, there is no significant difference between the cattle given the vitamin C and those not given it. In terms of the quality of the meat, however, there are significant differences in the fat marbling (Shimofuri), luster, firmness and texture of the meat.