To provide a plasma igniter capable of generating a discharge such as a pulse streamer discharge in a large region even by application of a low voltage, implementing powerful ignition by pulse voltage application in two or more stages, improving an air-fuel ratio (A/F), and reducing a CO2 emission amount.A plasma igniter includes an igniter part having a combustion chamber, and a discharge part arranged in such a manner that its discharge tip end is exposed to the combustion chamber. The discharge tip end has a column-shaped anode, an annular cathode arranged to be a predetermined interval away from an anode tip end part, and an annular floating electrode arranged between the anode tip end part and the cathode.