NOVELTY - Gas barrier film comprises: a base material (1); and an organic/inorganic hybrid gas barrier layer that is formed on the base material and has a compositionally gradient structure. The organic/inorganic hybrid gas barrier layer has a network structure comprising oxygen-silicon-oxygen linkages. The network structure contains an organic functional group having a carbon atom directly linked to a silicon atom of the linkages, and other element that exists in an oxide form in the interstitial location of the network structure or that is linked to an oxygen atom of the linkages.    USE - The gas barrier film is useful in a substrate of an electronic device and a packaging material (all claimed), where the electronic device is an organic thin film transistor, an organic light emitting device, an organic solar battery, LCD, mobile phones, notebook computers, and flexible display panel.    ADVANTAGE - The gas barrier film has excellent gas blocking properties, transparency, high adhesive force, high flexibility, hardness and strength, and controllable refraction index with respect to the base material, and can be stably, simply and economically manufactured.    DETAILED DESCRIPTION - Gas barrier film comprises: a base material (1); and an organic/inorganic hybrid gas barrier layer that is formed on the base material and has a compositionally gradient structure. The organic/inorganic hybrid gas barrier layer has a network structure comprising oxygen-silicon-oxygen linkages The network structure contains an organic functional group having a carbon atom directly linked to a silicon atom of the oxygen-silicon-oxygen linkages, and other element that exists in an oxide form in the interstitial location of the network structure or that is linked to an oxygen atom of the oxygen-silicon-oxygen linkages. The other element comprises at least one of alkali metal, alkaline earth metal, transition metal, post transition metal, metalloid, boron, and phosphorus. An INDEPENDENT CLAIM is included for manufacturing the gas barrier film, comprising (a) performing a sol-gel reaction on an organic/inorganic mixed solution including at least one organosilane compound of formula (A1l-A2m-A3nSi(OE1)p(OE2)q(OE3)r) (I), at least one silicate ester compound of formula (Si(OG1)a(OG2)b(OG3)c(OG4)d) (II), and an oxide precursor of at least one of the other elements to form a coating solution, (b) coating and curing the coating solution on a base material to form an organic/inorganic hybrid precursor layer, and (c) treating a surface of the organic/inorganic hybrid precursor layer with plasma of reactive gas to form an organic/inorganic hybrid gas barrier layer having a compositionally gradient structure.    A1-A3 = 1-20C-alkyl, 1-20C-fluoroalkyl, 6-20C-aryl, vinyl, acryl, methacryl or epoxy;    l, m, n, p, q, r = 0-3, where sum of l, m and n and p, q and r are 1-3, and sum of l, m, n, p, q and r is 4;    E1-E3 = 1-10C-alkyl, 1-10C-fluoroalkyl, 6-20C-aryl, 1-20C-alkyloxyalkyl, 1-20C-fluoroalkyloxyalkyl, 1-20C-alkyloxyaryl, 6-20C-aryloxyalkyl, or 6-20C-aryloxyaryl;    G1-G4 = 1-10C-alkyl, 1-10C-fluoroalkyl, 6-20C-aryl, 1-20C-alkyloxyalkyl, 1-20C-fluoroalkyloxyalkyl, 1-20C-alkyloxyaryl, 6-20C-aryloxyalkyl, or 6-20C-aryloxyaryl; and    a, b, c, d = 0-4, where sum of a, b, c and d is 4.    DESCRIPTION OF DRAWING(S) - The figure shows a cross sectional view of an organic/inorganic hybrid gas barrier film.    Base material (1)    Organic domain (2)    Gradient domain (3)    Inorganic domain. (4)