The object is to improve the bubble retention in a sparkling beverage such as a malt alcoholic beverage including a beer and a sparkling liquor, a sparkling alcoholic beverage produced without any malt and a carbonated refreshing beverage including a soda pop and a cream soda. Disclosed is a bubble stabilizer comprising, as an active ingredient, a water-soluble soybean polysaccharide which is produced by the heat-extraction from a soybean or a processed product of a soybean at a pH lower than the isoelectric point of a soybean protein and ranging from 2.4 to 4.0 at a temperature of 100.degree. C. or higher. The bubble stabilizer can be added to a malt alcoholic beverage such as a beer and a sparkling liquor, a sparkling alcoholic beverage produced without any malt or a carbonated refreshing beverage such as a soda pop and a lemon soda to thereby improve the bubble retention in the beverage.