A film forming device (100, 200, 300, 400), comprising: a chamber that includes a film forming chamber housing a container in which a gas barrier film is to be formed, the film forming chamber being adapted to be brought into a vacuum state in formation of the gas barrier film; and a gas supply pipe that includes a gas flow path and is adapted to be moved up and down along an axial direction, the gas flow path conducting, into the container, medium gas used for the formation of the gas barrier film, wherein the gas supply pipe is adapted to be inserted into the container housed in the film forming chamber, and adapted to supply the medium gas through the gas flow path, in the formation of the gas barrier film, wherein the gas supply pipe is adapted to be retracted from the film forming chamber and the gas flow path is adapted to be maintained in a decompression state in a standby time during which the formation of the gas barrier film is not performed; characterized in that the film forming device (100, 200, 300, 400) further comprises a decompression chamber that communicates with the gas flow path of the gas supply pipe in the standby time, wherein the gas flow path is maintained in the decompression state by decompression of the decompression chamber; wherein the film forming device (100, 200, 300, 400) further comprises a housing that stands up on and is supported by an upper chamber of the chamber along a vertical direction; a lower part of the sheath body is an opening that penetrates through the upper chamber; the housing comprising a sheath body, as well as the decompression chamber provided inside the sheath body; the gas supply pipe is moved up and down inside the decompression chamber, thereby being inserted into and pulled out from the film forming chamber, wherein the gas supply pipe is adapted to be inserted into and pulled out from the container through the chamber; wherein the film forming device (100, 200, 300, 400) further comprises a heater that is supported by the gas supply pipe, wherein the heater is adapted to be inserted into and pulled out from the container, following the insertion and pullout of the gas supply pipe. a chamber that includes a film forming chamber housing a container in which a gas barrier film is to be formed, the film forming chamber being adapted to be brought into a vacuum state in formation of the gas barrier film; and a gas supply pipe that includes a gas flow path and is adapted to be moved up and down along an axial direction, the gas flow path conducting, into the container, medium gas used for the formation of the gas barrier film, wherein the gas supply pipe is adapted to be inserted into the container housed in the film forming chamber, and adapted to supply the medium gas through the gas flow path, in the formation of the gas barrier film, wherein the gas supply pipe is adapted to be retracted from the film forming chamber and the gas flow path is adapted to be maintained in a decompression state in a standby time during which the formation of the gas barrier film is not performed; characterized in that the film forming device (100, 200, 300, 400) further comprises a decompression chamber that communicates with the gas flow path of the gas supply pipe in the standby time, wherein the gas flow path is maintained in the decompression state by decompression of the decompression chamber; wherein the film forming device (100, 200, 300, 400) further comprises a housing that stands up on and is supported by an upper chamber of the chamber along a vertical direction; a lower part of the sheath body is an opening that penetrates through the upper chamber; the housing comprising a sheath body, as well as the decompression chamber provided inside the sheath body; the gas supply pipe is moved up and down inside the decompression chamber, thereby being inserted into and pulled out from the film forming chamber, wherein the gas supply pipe is adapted to be inserted into and pulled out from the container through the chamber; wherein the film forming device (100, 200, 300, 400) further comprises a heater that is supported by the gas supply pipe, wherein the heater is adapted to be inserted into and pulled out from the container, following the insertion and pullout of the gas supply pipe.