PROBLEM TO BE SOLVED: To provide an agent for improving the aftertaste feeling of sweetness of a sweetener having high degree of sweetness such as sucralose, and a method for improving the aftertaste feeling of sweetness.SOLUTION: A sweetener having high degree of sweetness such as sucralose includes fermentative cellulose added thereto, to improve the aftertaste feeling of sweetness of the sweetener having high degree of sweetness.