PURPOSE: To provide a high current density glow discharge switch that is high in reliability with long-life and stable in quality by way of keeping off any concentration of electronic currents in and around the center of a plate electrode at the time of switching, and checking any possible temperature rise in this electrode.

CONSTITUTION: A cathode 3 and an anode 4 are composed each of a plate electrode 1 provided with a hole in the center and a cupped electrode 2 electrically connected to this plate electrode 1 in a state of being conducted. The cathode 3 and anode 4 are set up so as to oppose to the plate electrode 1, and at the outside, there is provided an insulating cylinder 7. Likewise, at the outside of this insulating cylinder 7, there is provided a coil 11 which generates a magnetic field. In addition, hydrogen gas is sealed in a hermetically sealed space composed of those of insulating cylinder 7, cathode 3 and anode 4.