To provide a method for producing a water-oil mixed fuel by which the mixed proportion of the water based on the combustible oil can be more heightened than the conventional one, and the water-oil mixed fuel having a calorific value equal to that of the combustible oil can be obtained, and to provide an apparatus for producing the water-oil mixed fuel.

A water-oil mixed fuel is produced as follows. A mixing adjuvant obtained by heating titanium oxide powder and black silica powder is added to an alkaline electrolyzed water, and the resultant water is stirred under the irradiation with ultraviolet rays to provide a functional water. The functional water is mixed with a combustible oil, and the resultant mixture is stirred under the irradiation with the ultraviolet rays to afford a water-oil mixture. The water-oil mixture is cooled to freeze a part thereof, and the unfrozen part is taken out to provide the water-oil mixed fuel. The water-oil mixed fuel can be regulated so as to have about 70% of the weight proportion of the water and about 30% of the weight proportion of the combustible oil based on the whole amount.