[Problem] To provide an oily thickener which has a high thickening effect on oily components, such as silicone oil, nonpolar organic compounds, and low-polar organic compounds, and is easy to handle. [Solution] Surface-hy-drophobicized cellulose nanofibers for an oily thickener according to the present invention have an average thickness of 3-200 nm, and an average length of 0.1 µm or more, wherein an aqueous dispersion containing 1 wt% of the cellulose nanofibers has a viscosity value of 700-2100 mPa·s, hydroxy groups in cellobiose units thereof are substituted with a vinyl ester and/or an organic acid vinyl ester, and the degree of the substitution is 0.2-0.8.
