With regard to compositions derived from active ingredients and other additives in medical, food and industrial fields, there have been problems that the active ingredients cannot be uniformly mixed, and that the active ingredients become segregated and lose uniformity as the active ingredients undergo transport, input, and filling processes. There is provided a cellulose powder which improves the uniformity of compositions containing active ingredients or other additives to prevent segregation of the active ingredients, wherein the cellulose powder contains cellulose I type crystals, has an average particle diameter of less than 30 μm, a powder density of 0.1 to 0.45 g/cm3, a tapping density of 0.1 to 0.5 g/cm3, a repose angle of 35 to 50°, a specific surface of more than or equal to 0.1 m2/g and less than 20 m2/g, an internal friction angle of 36 to 42°, and is a cellulose powder including a secondary flocculation structure in which primary particles are flocculated.
