To improve the rate of separation and sedimentation of precipitation in fractionation of a soluble fraction comprising 7S globulin and an insoluble fraction comprising 11S globulin of soybean protein.

A method for improve the rate of separation and sedimentation of precipitation comprises heating a solution containing soybean protein to 30 to 75C under acidic conditions of pH 3.8 to 6.8 and then fractionating it into a soluble fraction and an insoluble fraction at an ionic strength of 0.02 or more and a pH value of 4.5-5.6.