PURPOSE: To obtain the emulsifier excellent in emulsifying ability and stability form naturally occurring material by suing an ovalbumin derivative consisting of a hydrolysate from the C end side of ovalbumin and having about 4.0-4.3×104 mol.wt. as the effective component.

CONSTITUTION: An ovalbumin derivative consisting of the hydrolysate from the C end side of ovalbumin and having about 4.0-4.3×104mol.wt. is used to obtain an emulsifier high in safety and emulsifying ability from naturally occuring material. The ovalbumin separated from egg albumen is firstly dissolved in water by the ammonium sulfate process, etc., to produce the emulsifier. Protease such as subtilisin capable of uniquely hydrolyzing from the C end side is allowed to act on the aq.soln. to hydrolyze the ovalbumin, and the ovalbumin derivative as the effective component is obtained. The soln. of the derivative as such or the product obtained by spray-drying the soln. is used as the emulsifier.