A thermoplastic resin film excellent in slipperiness, wear resistance and transparency contains 0.05 to 0.5 wt. % of specified fine particles of composite oxide comprising silica, alkali metal oxide, and at least one inorganic oxide other than silica, wherein the fine particles satisfies the following expression (I):S .gtoreq.10,000/(Dp*SG) (I)wherein S indicates the specific surface area (m.sup.2 /g) of the fine particles of composite oxide, Dp indicates the average diameter (nm) of the fine particles, and SG indicates the true specific gravity thereof. The film is preferably a polyester film having a hazing value of 5% or less. It is suitable for use as magnetic tape, capacitor, photographic film and pressure-sensitive adhesive tape. The film is manufactured by adding a silicate of alkali metals, ammonium or organic bases and an alkali-soluble inorganic compound simultaneously to an alkali solution with pH 9 or above, generating fine particles of composite oxide without any control of the pH of this reaction solution, adding the obtained sol to a thermoplastic resin and/or the reaction system thereof, and processing of a film.