Oil/water mixture recovered from sea surface, etc. is emulsified without the use of any emulsifier and subjected to combustion. Boat (300) is equipped with spilled oil recovery unit (310) for recovering oil having been spilled onto natural sea area; emulsification unit (100) devised so that while discharging through a liquid discharge nozzle any oil/water mixture (121) having been recovered by the spilled oil recovery unit (310), the oil/water mixture is crushed by a high-speed airstream emitted through a gas emission nozzle disposed around the liquid discharge nozzle to thereby produce an oil/water emulsion; and combustion unit (200) capable of combustion of the emulsion produced by the emulsification unit (100).