To provide an internal combustion engine for generating electric power using explosive combustion for enhancing electric power generation efficiency by inexpensive renewable combustible powder with much ash or liquid fuel.

A lower part of a gap between a cylinder of an internal combustion engine for generating electric power and a piston at the inner side is configured to be wide. The gap is filled with water, the ash or carbide generated when performing explosive combustion of combustible powder or liquid is peeled off by the pressure of the water, or is blown off by water steam.