A gas-adsorbing member is charged in low gas-permeable container (7) through its opening portion, wherein low gas-permeable container (7) is constituted by a hollow cylindrical metal member which is opened at its one end and is sealed at its other end and, also, has body portion (9) extending from the one end to the other end thereof such that the length of the body portion is equal to or larger than the maximum width of the end portions. Then, a sealing member is installed within the opening portion and near the opening portion. Then, the sealing member is molten by being heated. Thereafter, the sealing member within the opening portion is cooled to be solidified, thereby attaining sealing of the opening portion. Thus, it is possible to provide a gas-adsorbing-device fabricating method capable of suppressing degradations of the gas-adsorbing member and capable of reducing the fabrication costs.