A method of producing silane-modified cationized cellulose that has excellent aqueous dispersibility, including: a step (1) of cationizing water-soluble cellulose ether in a presence of alkali in a mixed solvent of a water-compatible organic solvent to obtain slurry comprising cationized cellulose a step (2) of adding acid to said slurry and neutralizing said alkali a step (3) of reacting said cationized cellulose obtained after said neutralization with an aminosilane compound and a step (4) of drying the obtained slurry, wherein: drying is conducted in step (4) at 115-160° C. until weight loss on drying is 5% by weight or less, or there is also including a step (5) of adding a water-compatible organic solvent or a mixed solvent of a water-compatible organic solvent and water to the cationized cellulose after the neutralization so that water content in a whole solvent that contacts the cationized cellulose is 10% by mass or less.
