INTERNAL COMBUSTION ENGINE

The present invention aims at effectively improving a propagation speed of a flame utilizing an electromagnetic wave in an internal combustion engine that promotes combustion of an air fuel mixture utilizing the electromagnetic wave. The present invention is directed to an internal combustion engine including: an internal combustion engine main body formed with a combustion chamber; and an ignition device that ignites the air fuel mixture in the combustion chamber, wherein combustion cycles, in which the ignition device ignites and combusts the air fuel mixture, are repeated. The internal combustion engine further includes: an electromagnetic wave emission device that emits an electromagnetic wave to the combustion chamber from the emission antenna; a flame propagation estimation part that performs an estimation operation of estimating a propagation condition of a flame while the flame is propagating in the combustion chamber; and a control unit that controls the electromagnetic wave emission device based on an estimation result of the estimation operation.