Ejection and stop of a powder flow are switched while maintaining a once generated steady flow without stopping it. A processing nozzle includes a supply source of a fluid containing a powder, a first channel through which the fluid supplied from the supply source passes, a second channel that supplies the fluid to an ejection port of the nozzle, a third channel that releases the fluid outside the nozzle, and a switch that causes the first channel and the second channel to communicate with each other when supplying the fluid to the ejection port, and causes the first channel and the third channel to communicate with each other when not supplying the fluid to the ejection port.