Disclosed is a cellooligosaccharide composition comprising, as the main ingredient, at least one cellooligosaccharide selected from the group consisting of cellobiose, cellotriose, cellotetraose, cellopentaose and cellohexaose, which is in the powdery form having an average L/D value of 3.0 or lower, a bulk density of 0.80 g/mL or lower and an angle of repose of 60.degree. or lower.