In a combustion device which sprays liquid fuel and combusts it, an object is to promote combustion reaction and improve combustion efficiency, and suppress exhaustion of ash dust, carbon monoxide, nitrogen oxide, by reducing spray particle diameter and reducing kinetic momentum. A spray nozzle is provided with upper and lower channels 28 and 29 from respective surfaces, the two channels form a cross shape, and become a fuel spray hole by communication of an intersecting part 30. A guide member 23 is provided, in contact with the upstream-side channel 28, in a position overlapped with the intersecting part (fuel spray hole) 30 with respect to the spray direction of the spray nozzle. Spray fluid (liquid fuel) is branched with the guide member 23 from the fuel fluid duct 21 connected to the spray nozzle, passes through the upstream-side channel 28, to the intersecting part 30, and is sprayed. The spray fluid forms opposed flows toward the intersecting part 30 in the upstream-side channel 28 to collide with each other at an obtuse angle of 90° or greater, then is sprayed from the intersecting part 30, to form a thin fan-shaped liquid film 31. The liquid film is divided by a shearing force from the peripheral gas, atomized into spray particles 32.