PURPOSE: To prepare an edible cellulosic material having excellent color and palatability, and useful as a food additive, by immersing pressed beet pulp discharged from the sugar extraction process in a hypochlorous acid (salt) solution of a specific concentration, followed by washing with water and drying.

CONSTITUTION: 1pt.wt. of pressed beet pulp discharged from the sugar extraction process is immersed in about 2W3pts.vol. of solution of hypochlorous acid or its salt having an effective chlorine concentration of 0.1W0.5wt/vol% and adjusted to an initial pH of 6.5W7.5, at room temperature for about 4W5hr. After the treatment, the pulp is, if necessary treated with an aqueous solution of a reducing agent such as sodium hydrosulfite or sodium bisulfite to remove hypochlorous ion, and washed with water and dried to obtain the objective edible cellulosic material. The material is suitable as a food additive to increase the content of cellulose in the food.