The invention provides a preparation process of organic-group-modified zeolite fine particles excellent in stability of particle size and to be used for electronic materials or the like. The preparation process comprises a first step of obtaining a liquid containing zeolite seed crystals having a particle size of 80 nm or less which are formed in the presence of a structure directing agent, a second step of adding an organic-group-containing hydrolyzable silane compound to the liquid obtained by the first step, and a third step of maturing the liquid of the second step at temperature higher than that of the first step. A dispersion liquid of zeolite fine particles obtained by the process.