PURPOSE: To generate a designated peak voltage on the secondary side of an ignition coil even if the ignition interval of multiple ignition is made narrower by providing a spark plug adapted to fly sparks by high voltage generated in the secondary side coil and a high-voltage diode connected in a series to the secondary side coil.

CONSTITUTION: In a construction circuit of a multiple ignition type engine igniter, a high-voltage diode 1b is connected in a series to the secondary side output of an ignition coil 8. Whereupon, the ignition operation process where high voltage is generated in the secondary side coil of the ignition coil 8 to force a spark plug to fly sparks, thereby igniting an engine is similar to the conventional operation process. As the high voltage diode 16 is connected in a series to the secondary side coil of the ignition coil 8, however, even if the ignition interval is made narrower, the mutual intervention of the secondary voltage generated in the secondary side of the conventional ignition coil 8 can be prevented by the high voltage diode 16. Accordingly, it is possible to generate a designated peak voltage of the ignition coil.