The present invention has its object to provide a novel emulsifier which is obtainable from an edible yeast and is highly safe and shows by itself a high level of emulsifying property and high emulsion stability; a water-soluble composition containing a liposoluble substance, together with the emulsifier; and methods of producing these. The present invention includes: an emulsifier which comprises, as an active ingredient, a carbohydrate- and protein-based complex derived from a culture fluid obtained by cultivating an edible yeast; a water-soluble composition which comprises an emulsifier and a liposoluble substance; and a method of producing the emulsifier and the water-soluble composition.