A gas discharge tube (1), wherein a side tube member (14) is formed of glass with a metal employed for joint portions of a stem (4) and side tube member (14), so as to prolong the lifetime of the discharge tube while lowering a discharge tube assembling temperature, a first metal circumferential portion (15) provided on the stem (4) and a second metal circumferential portion (16) provided on the side tube member (14) being utilized as the joint portions, this enabling the discharge tube (1) to be miniaturized.
