To reduce an explosion temperature so as to perform complete combustion by mixing light oil with water, performing atomizing, and increase a surface area.

Fuel formed by mixing light oil with water at a constant ratio by means of a venturi formula is atomized into a nano size by a constant rate mixing atomizer 3, and it is supplied from a light oil tank 1 and a water tank 2 to an injection pump 6, and complete combustion is performed. Water added fuel is atomized in the nano size, and thereby, water and light oil become a complete emulsification condition, and thereby, graphite is not generated. A water adding operation being performed, explosion is generated by the function of hydrogen and oxygen in water molecule at a position where a combustion temperature is low, and thereby, Nox is not generated. It is possible to save fuel by performing a water adding operation.