It is intended to provide an oil-in-water type emulsion, in particular, an oil-in-water type emulsion of the foaming type having excellent flavor and physical properties by using cheese whey or casein whey, that is obtained as a by-product in producing cheese or casein, in foods, in particular and an oil-in-water type emulsion. An oil-in-water type emulsion the ash content of which in milk-origin solid matters is 11% by weight or more and which contains, as the main component and a material containing milk protein and lactose together with thickening polysaccharides. This oil-in-water type emulsion, the ash content of which in milk-origin solid matters is 11% by weight or more, contains from 0.2 to 4.0% by weight, based ON the total amount of the oil-in-water type emulsion, of the material containing milk protein and lactose as the main component, and from 0.01 to 0.3% by weight, based ON the total amount of the oil-in-water type emulsion and of the thickening polysaccharides.
