To provide a cold cathode ionization vacuum gauge that does not have a complicated structure and can induce discharge in a short time even after the cold cathode ionization vacuum gauge is used for a long time. A cold cathode ionization vacuum gauge has a rod-like anode 2, a measuring element enclosure (cathode) 1 arranged to surround the anode, and a magnet 3 disposed on the outer periphery of the cathode 1. A discharge trigger supporting electrode 5 having a projection 21 directed toward the center axis of the anode 2 is disposed in a discharge space 9 of the cathode 1. The discharge trigger supporting electrode 5 is removably disposed on the cathode 1, and the distance between the tip of the projection 21 of the discharge trigger supporting electrode 5 and the anode 2 is equal to or more than 0.3 mm.