Disclosed is a device for automatically opening or closing a gas barrel valve. The device includes: a main plate installed so as to move up and down and to align the position of a gas barrel loaded in a cabinet; a gas barrel connecting portion installed on the lower portion of the main plate, separating an end cap from the gas barrel and storing the end cap, and then automatically screw-coupling a connector holder to a gas spray nozzle; a valve handle unit installed on the main plate so as to rotate around a first shaft and rotating a valve handle of the gas barrel such that the valve handle is locked or unlocked, while encompassing the valve handle of the gas barrel; and a valve handle opening or closing unit installed on the upper portion of the main plate so as to operate the valve handle unit in a direction, in which a valve of the gas barrel is opened.