[Problem] To provide a dispersion fluid for inorganic oxide particles that is useful in the production of an optical base coating fluid suitable for the formation of a coating film (curable film for a hard-coat layer film, a primer layer film, etc.) having excellent mechanical strength (abrasion resistance, wear resistance), appearance conformance (cloudiness, interference fringes), adhesiveness, weather resistance, light resistance, crack resistance, and optical properties (high refractive index). [Solution] A dispersion fluid for water and/or an organic solvent that includes a linked crystalline inorganic oxide particle group and comprises: (1) crystalline inorganic oxide particles including silicon and at least one type of metal element (M2) selected from a group comprising titanium, zirconium, niobium, cerium, and zinc; (2) a coating substance that coats the particles (1) and comprises a composite oxide including silicon and at least one type of metal element (M1) selected from a group comprising zirconiu
