A combustion burner configured to mix combustible gas generated by gasification of a waste product and combustion air together, and supply the combustible gas and the combustion air to a combustion chamber, the combustion burner comprising: a gas duct forming a gas flow path along which the combustible gas moves; an air duct disposed along an external surface of the gas duct, the air duct forming an air flow path along which the combustion air taken in from outside moves, the air flow path being formed between the air duct and the gas duct; and a branching post connected to the gas duct in the gas flow path, the branching post discharging the combustible gas from the gas duct while dividing the gas flow path into a plurality of flow paths, characterized in that the burner further comprises a straightening plate disposed in the air flow path and having an opening that controls an amount of the combustion air passing through the opening and the air flow path has a region defined downstream of the combustion air with respect to the straightening plate, the region being constructed of an upper air chamber, a lower air chamber, a left air chamber, and a right air chamber separated from each other and positioned above and below the gas flow path, and on the left and right sides of the gas flow path, respectively, the branching post includes discharge nozzles configured to discharge the combustion air guided from the upper air chamber and the lower air chamber to the branched flow paths of the combustible gas, and further discharge nozzles configured to discharge the combustion air guided from the left air chamber and the right air chamber to the branched flow paths is provided at end portions of the gas duct. a gas duct forming a gas flow path along which the combustible gas moves; an air duct disposed along an external surface of the gas duct, the air duct forming an air flow path along which the combustion air taken in from outside moves, the air flow path being formed between the air duct and the gas duct; and a branching post connected to the gas duct in the gas flow path, the branching post discharging the combustible gas from the gas duct while dividing the gas flow path into a plurality of flow paths, characterized in that the burner further comprises a straightening plate disposed in the air flow path and having an opening that controls an amount of the combustion air passing through the opening and the air flow path has a region defined downstream of the combustion air with respect to the straightening plate, the region being constructed of an upper air chamber, a lower air chamber, a left air chamber, and a right air chamber separated from each other and positioned above and below the gas flow path, and on the left and right sides of the gas flow path, respectively, the branching post includes discharge nozzles configured to discharge the combustion air guided from the upper air chamber and the lower air chamber to the branched flow paths of the combustible gas, and further discharge nozzles configured to discharge the combustion air guided from the left air chamber and the right air chamber to the branched flow paths is provided at end portions of the gas duct.