Provided is a technology for uniformly increasing atmosphere temperature while rapidly achieving a desired uniform atmosphere composition. A combustion apparatus is provided with: a combustion part including a combustion space with a combustible gas inlet which is opened toward the combustion space for allowing the entry of a combustible gas, an air inlet which is opened toward the combustion space for allowing the entry of air, and a combustion gas outlet for discharging a combustible gas to the outside; and a regulated gas through channel part including a regulated gas outlet for discharging the gas prepared into a desired composition to the outside, the regulated gas outlet located adjacent to the combustion gas outlet and having an opening facing the combustion gas immediately after being discharged from the combustion gas outlet.