Abstract: A gas-filled discharge tube includes a tubular body formed of an electrically insulating material, and has engaging portions respectively at opposite ends thereof. A pair of electrode bases are provided; at least one of the electrode bases is formed of an electrically conducting thin metal sheet, airtightly adhered to the respective open ends. A pair of discharge electrodes are provided; the discharge electrodes have flange portions which are engaged with the respective engaging portions and sandwiched between the tubular body and the respective electrode bases. One of the electrode bases is formed with a gas filling bore by a laser beam for filling an inert gas. The gas filling bore is welded by the laser beam after the inert gas is filled in the tubular body, so as to seal and enclose the inert gas therein.