Yogurt containing lactic acid bacteria and Bifidobacteria, to which one or more kinds of sweet substances selected from a group consisting of palatinose, palatinite, maltose, maltitol, starch syrup, reducing starch syrup and trehalose as well as a refined fish oil containing highly unsaturated fatty acids such as DHA and EPA are added, is packed in an oxygen blocking hermetic package. The yogurt contains highly unsaturated fatty acids and has good flavor and taste, as well as excellent product quality stability, and does not generate a fishy odor during normal storage periods.