Disclosed is an extremely stable liquid dispersion of fine core/shell complex oxide particles, wherein the surface negative charge and the core covering ratio by the shell are high. The fine core/shell complex oxide particles are obtained by covering the surfaces of core particles, namely the surfaces of fine oxide particles or fine complex oxide particles that do not contain silicon and/or aluminum as a main component, with shells that are composed of a complex oxide which contains silicon and aluminum as main components. The weight ratio of the silicon content to the aluminum content in the shells in terms of oxides, namely SiO2/Al2O3 is within the range of 2.0-30.0.