[Problem] To provide a dispersion containing surface-modified silica nanoparticles highly dispersed in an organic dispersion medium and also having high transparency and storage stability. [Solution] Disclosed is a method for producing surface-modified silica nanoparticles comprising: preparing a first silica nanoparticle dispersion containing silica nanoparticles and an aqueous dispersion medium; replacing the aqueous dispersion medium in the first silica nanoparticle dispersion with an organic dispersion medium comprising at least one selected from cyclic esters or cyclic amides, to obtain a second silica nanoparticle dispersion; and mixing the second silica nanoparticle dispersion with a silane coupling agent represented by the formula (1): (each R 1 is independently a hydrocarbon group of C 1 to C 20 and R 2 is a hydrocarbon group of C 1 to C 3 ), to modify the surface of the silica nanoparticles.