PURPOSE: To improve the combustion efficiency of each of various kinds of combustion engines while permitting oxigen ions to exist in the combustion chamber of the engine by supplying ionized oxigen into the combustion air of the engine.

CONSTITUTION: High voltage generated by a private transformer is applied via an electric conductor 10 to an electric accelerating electrode 2 supported by an insulator 8, and corona discharge is induced between said accelerating electrode and an electron discharging electrode 3. Oxigen gas in air introduced from an air intake port 4 during a corona discharge is resolved in an electric field 5 produced by the corona discharge, and ionized. Oxygen ions 6 produced in this way are introduced from an ion introducing port 7 into a fuel mixed gas intake passage. In this way, the mixing state of oxygen and fuel in a combustion port can be made satisfactory, while it is possible to decompose and atomize the mixed gas.