Abstract: A thermal spray gun of the present invention is capable of forming a good-quality ceramic spray coating. According to the machine, a flame generated in a combustion chamber of the machine is sent into a passage formed from the combustion chamber and through a discharge port that communicates with the combustion chamber, and then the flame is discharged from the discharge port to outside of the machine. A spray material is fed to the flame passing through the passage so that the spray material can be softened or melted by the flame and can be jetted out. An auxiliary fuel is fed to the flame passing through the passage to increase a temperature of the flame.