COMBUSTION DEVICE

PROBLEM TO BE SOLVED: To suppress the generation of NOx throughout a wide range of combustion by reducing a flame hole load in a primary flame hole during a strong combustion in which the amount of fuel supply is increased, preventing a primary combustion flame from being lengthened and shortening the stagnation time of gas in the high temperature area of the primary combustion flame. SOLUTION: A combustion device B comprises a box body 29 for covering a burner main body 21 having a flame hole plate 2T with a primary flame hole 26 composed of a plurality of slits 28 on its upper part or the primary flame hole 26 of the flame hole plate 27 and having an inner part as a primary combustion chamber 22, and a rectangular secondary flame hole 23 provided on the upper part of the box body 29. The combustion device further comprises secondary air supply parts 20 provided in the proper parts of the box body 29 below the primary flame hole 26 and flow changing members 30 for changing the flows of secondary air for combustion from the secondary air supply parts 20 so as to be separated from the primary flame hole 26 and which are provided upright so as to be opposed to each other outside the primary flame hole. A space S for guiding gas fuel outside is provided below the primary flame hole 26 of the flame hole plate 27.