PURPOSE: To efficiently form thermally sprayed coating layers having high quality by injecting a molten thermal spraying material in such a manner that the outside circumference of the main jet consisting of the gaseous flow including said material is enclosed by annular protective gaseous flow having nearly the same temp. and flow rate as the temp. and flow rate of said gaseous flow.

CONSTITUTION: A high-temp. combustion gas formed by burning gaseous fuel 5 with auxilairy combustion gas 6 in a combustion chamber 7 is supplied into a circular cylindrical gap 2 provided with a sleeve 10 of a nozzle body 1. Furthermore, the thermal spraying material 4 is supplied through a supply pipe 3 into the sleeve 10. The gaseous flow 8 contg. the thermal spraying material is thereby formed in the sleeve 10 in the nozzle 11A and is ejected as the main jet 14 contg. the thermal spraying material in the molten state from a nozzle outlet 16A to form the thermally sprayed coating layers 13 on the surfaces of a material 12 to be thermally sprayed. On the other hand, the gaseous flow 9 which does not contain the thermal spraying material and flows on the outside circumference of the sleeve 10 forms the annular protective gaseous flow 15 having nearly the same temp. and gaseous flow rate as the temp. and flow rate of the main jet 14. The momentum holding distance of the main jet 14 is thereby increased and the spread thereof is suppressed; then are obtd. without being affected by external environment.