The present invention provides: a method of manufacturing a gas barrier film, which is manufactured at high productivity, and has extremely high gas barrier performance and stability thereof with time, excellent surface smoothness and bending resistance, and high durability; a gas barrier film obtained using the method; and an organic photoelectric conversion element using the gas barrier film. In the method, after forming a coated layer by applying a coating liquid containing polysilazane to a substrate, a gas barrier layer is formed by applying vacuum ultraviolet light to the coated layer surface thus formed. The method is characterized in that the coated layer is irradiated with the vacuum ultraviolet light, while drying the solvent in the e coated layer.