An oil-in-water emulsion satisfies all of the following four criteria: the protein content is from 0.1 to 10 mass %; a marine-derived potassium salt is contained; the mass ratio between sodium and potassium (Na:K) is from 1:0.5 to 1:10; and the oil component content is from 0.3 to 49 mass %. Preferably, the non-fat milk solids content is less than 3 mass %. It is also preferable that the oil-in-water emulsion contains a plant-based milk, or contains a plant-derived protein material.