The method for producing a filled container of the present invention includes: providing a metal storage container, at least an inner surface of which is formed of a manganese steel and in which the inner surface has a surface roughness Rmax of 10 μm or less; performing fluorination by bringing the inner surface of the storage container into contact with a gas containing at least one first fluorine-containing gas selected from the group consisting of ClF3, IF7, BrF5, F2, and WF6 at 50° C. or lower; purging the inside of the storage container with an inert gas; and filling the inside of the storage container with at least one second fluorine-containing gas selected from the group consisting of ClF3, IF7, BrF5, F2, and WF6.