Abstract: A switching apparatus obtains a large switching current by multiplying the number of electrons emitted by field emission from a cold cathode. The switching apparatus is driven by an optical wave and includes a recess portion of an insulation layer formed on a silicon substrate, a cold cathode formed on the insulation layer comprising many comb-tooth like tips extending from one side above the recess portion, a gate electrode disposed on the recess portion on the side of the cold cathode, an anode formed on the insulation layer and extending from another side opposed facing to the one side above the recess portion, an optically transparent sealing member comprising a recess portion on its under surface for enclosing a dilute nitrogen gas in a vacuum space, and a semiconductor laser, supported on the sealing member by a support member, for irradiating a laser beam through the sealing member into the space.