A method of producing a gas barrier film comprises the steps of: supplying a material gas including silane gas, ammonia gas and at least one of nitrogen gas and hydrogen gas to a process chamber; keeping the process chamber at an internal pressure of 20 to 200 Pa; holding a substrate in the process chamber at a substrate temperature of not more than 70° C.; forming a bias potential of −100 V or less at the substrate; and supplying power P (W) to the material gas so as to have a ratio P/Q of the power P to a silane gas flow rate Q (sccm) of 15 to 30 W/sccm to generate plasma, thereby depositing a silicon nitride layer on a surface of the substrate.