PURPOSE: To destroy the carbon in a combustion chamber by fire to be removed, by arranging an electrode plate facing to the combustion chamber and providing a means which applies high voltage in a period while combustion gas exists in the combustion chamber.

CONSTITUTION: A ring-shaped conductive plate 17, being embedded in the internal wall of a cylinder liner 16, is connected with a high voltage generating device 19 by an electrode terminal 18. A voltage application timing control device 19c sets a period that voltage is applied to the electrode terminal 18 on the basis of a fuel injection pressure sensor 19a and a crank sensor 19b. A high voltage generating circuit 19d generates the high voltage to be output only for the application period set by the control device 19c. In this way, the improvement of output and fuel consumption is promoted because a fine particle of carbon or the like can be prevented from cohesion and destroyed by fire in a combustion chamber.