Abstract: Finely divided fibrous cellulose particles having a high viscosity, suspension stability and water-retaining property are produced by suspending cellulose particles in water or an organic liquid, and subjecting the resultant cellulose particle slurry to a wet grinding procedure in a solid medium-agitation type grinder in which the cellulose particles are agitated and ground with solid medium particles, for example, glass beads, to an extent such that the cellulose particles are divided into fine fibrous cellulose particles having a water-retaining power WRP of 150% or more in accordance with an equation (I):WRP(%)=(A-B)/B.times.100 (I)wherein A represents the weight of a sample of the resultant cellulose particle suspension centrifugally hydroextracted at an acceleration of 3,000 G for 15 minutes, and B represents the weight of the sample dried at 105.degree. C. for 5 hours or more.