To provide a plasma generation device capable of efficiently generating plasma by taking an electromagnetic wave out of a space irradiated with the electromagnetic wave and generating the plasma by supplying the taken-out electromagnetic wave to a reaction vessel.

A plasma generation device comprises a closed space 6 irradiated with an electromagnetic wave, an antenna 4 having one end 7 inserted into the closed space 6 and the other end 8 provided outside the closed space 6, a reaction vessel 3 placed outside the closed space 6 while a tip 9 of the other end of the antenna 4 is put inside the reaction vessel, and impedance adjusting means 15 which is present to match impedance in the closed space 6, the antenna 4 receiving an electromagnetic wave of a stationary wave at the one end 7 and generating plasma at the tip 9 of the other end 8.