NOVELTY - A gas barrier film (1a) has gas barrier layer (2) containing silicon, oxygen and carbon on at least one surface of a base material (1). The distribution curve of each element contained in gas barrier layer is measured based on element distribution along depth direction, by X-ray photoelectron spectroscopy. The carbon atomic ratio of gas barrier layer is less than silicon atomic ratio, in a region extending from the surface of gas barrier layer to a distance of 90% or more. The silicon atomic ratio of gas barrier layer is less than oxygen atomic ratio.    USE - Gas barrier film. Uses include but are not limited to liquid crystal display device, organic electroluminescent element, solar cell, electronic paper, timepiece, signboard advertisement, signal apparatus, optical storage medium, electrophotographic copier, photosensor, etc.    ADVANTAGE - The environmentally-friendly gas barrier film has excellent gas barrier property even in high temperature and high humidity, and flexibility, and cracking resistance.    DETAILED DESCRIPTION - A gas barrier film has gas barrier layer containing silicon, oxygen and carbon on at least one surface of a base material. The distribution curve of each element contained in gas barrier layer is measured based on element distribution along depth direction by X-ray photoelectron spectroscopy. The carbon atomic ratio of gas barrier layer is less than silicon atomic ratio, in a region extending from the surface of gas barrier layer to a distance of 90% or more. The silicon atomic ratio of gas barrier layer is less than oxygen atomic ratio, in a region extending from the surface of gas barrier layer to a distance of 90% or more. The carbon distribution curve has 2 or more extreme values. The absolute value of the difference between the maximum value and the minimum value of the carbon atomic ratio in the carbon distribution curve is 5% or more. The maximum of the oxygen distribution curve closest to the surface of the gas barrier layer on the base material side is the maximum value among the maxima of the oxygen distribution curve in gas barrier layer. An INDEPENDENT CLAIM is included for manufacture of the gas barrier film.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of gas barrier film structure.    Base material (1)    Gas barrier film (1a)    Smooth layer (2)    Gas barrier layer (3)