To provide a discharge tube having improved stability of operating voltage to repeated discharges. The discharge tube includes a cylindrical insulating hollow body having openings at least at both ends and at least a pair of sealing electrodes facing to each other for closing the openings so as to seal a discharge control gas inside the body, wherein a discharge trigger film made of a conductive material is formed on the inner circumferential surface of the insulating hollow body, each of the sealing electrodes has a convex portion projecting into the insulating hollow body and a discharge active layer(s) that is/are made of a material having higher electron emission characteristics than that of the sealing electrodes.