A film forming device comprising: a chamber which has a film-forming chamber accommodating a container for forming a gas barrier film, and in which the film-forming chamber is configured to be in a vacuum state when the gas barrier film is formed; a gas supply pipe which has a first gas flow channel which is configured to introduce a medium gas used for forming the gas barrier film into the container and which is configured to move upward and downward along an axis line direction thereof; a cylinder in which the gas supply pipe is configured to move upward and downward; and a heat generating body which is configured to heat when power is supplied, wherein the cylinder has a gas supply port which is configured to supply the medium gas from outside, wherein the gas supply pipe includes a second gas flow channel which is configured to move upward and downward between a film-forming position where film-forming is performed and a standby position where no film-forming is performed, and is configured to cause the gas supply port of the cylinder and the first gas flow channel to be in communication with each other at the film-forming position, characterized in that the film forming device further comprises a shielding gate, which is configured to block communication between the film-forming chamber and the first gas flow channel when the gas supply pipe is retreated from the film-forming chamber, the second gas flow channel is provided in a seal which is fitted into the gas supply pipe and is slidably pressed to the cylinder, the seal includes a first seal ring, a second seal ring which is provided at a distance from the first seal ring in the axis line direction, and a spacer which is provided between the first seal ring and the second seal ring and has a diameter smaller than diameters of the first seal ring and the second seal ring, and the second gas flow channel is provided in the spacer. a chamber which has a film-forming chamber accommodating a container for forming a gas barrier film, and in which the film-forming chamber is configured to be in a vacuum state when the gas barrier film is formed; a gas supply pipe which has a first gas flow channel which is configured to introduce a medium gas used for forming the gas barrier film into the container and which is configured to move upward and downward along an axis line direction thereof; a cylinder in which the gas supply pipe is configured to move upward and downward; and a heat generating body which is configured to heat when power is supplied, wherein the cylinder has a gas supply port which is configured to supply the medium gas from outside, wherein the gas supply pipe includes a second gas flow channel which is configured to move upward and downward between a film-forming position where film-forming is performed and a standby position where no film-forming is performed, and is configured to cause the gas supply port of the cylinder and the first gas flow channel to be in communication with each other at the film-forming position, characterized in that the film forming device further comprises a shielding gate, which is configured to block communication between the film-forming chamber and the first gas flow channel when the gas supply pipe is retreated from the film-forming chamber, the second gas flow channel is provided in a seal which is fitted into the gas supply pipe and is slidably pressed to the cylinder, the seal includes a first seal ring, a second seal ring which is provided at a distance from the first seal ring in the axis line direction, and a spacer which is provided between the first seal ring and the second seal ring and has a diameter smaller than diameters of the first seal ring and the second seal ring, and the second gas flow channel is provided in the spacer.