A plasma generation device, including: an ionization unit that ionizes gas in a target space; an electromagnetic wave oscillator that oscillates an electromagnetic wave to be radiated to the target space; and an antenna that radiates the electromagnetic wave supplied from the electromagnetic wave oscillator to a gas ionization region in which gas ionized by the ionization unit is provided. The ionization unit ionizes gas and the antenna radiates the electromagnetic wave thereto to generate plasma. A plurality of strong electric field regions are formed around the antenna when the electromagnetic wave is supplied from the electromagnetic wave oscillator. The strong electric field region is a region stronger in electric field than the surrounding area. The ionization unit ionizes gas around the plurality of strong electric field regions, or gas around a plurality of regions in which immediately before strong electric fields come into existence.