To obtain a new emulsion fuel which does not separate a fuel oil from water and maintains an emulsified state even in long-term preservation even without using an additive such as an emulsifying agent, stabilizer, etc., does not separate a fuel oil from water even by change in temperature, has excellent long-term storage stability and exhibits stable and optimal combustion efficiency and to provide a method for producing an emulsion fuel, which easily and surely produces the emulsion fuel.

The mulching fuel comprises a fuel oil and functional water without adding a surfactant and an emulsifying agent. Especially the function water is electronic water and harmonic reducing water, preferably the emulsion fuel contains further sodium chloride. The method for producing the emulsion fuel comprises a first process for mixing a fuel oil with harmonic reducing water with stirring to give an emulsion and a second process for mixing the emulsion obtained by the first process with electronic water with stirring.