A vacuum switch apparatus has an electrically insulating vacuum enclosure which is evacuated to a vacuum degree of 2.times.10.sup.-2 Torr or less. One set of anode and cathode electrodes is arranged in the vacuum enclosure, having capacity which permits the flow of a discharge current of at least 1 KA therebetween and being operable to switch the discharge current at least 10.sup.6 shots. A high voltage power supply applies a high voltage of at least 20 KV across the anode and cathode electrodes. An electron beam irradiation unit irradiates an electron beam on the anode electrode through the cathode electrode. A control electrode is arranged between the beam irradiation unit and the cathode electrode, for controlling passage and interception of the electron beam. A control voltage power supply applies a control voltage to the control electrode. An electromagnetic coil is arranged at least exteriorly of the vacuum enclosure, for generating electromagnetic force which prevents the electron beam, emitted from the electron beam irradiation unit and reaching the anode electrode through the control and cathode electrodes, from being scattered.