<p>A yarn processing device having high yarn processing performance is provided. The yarn processing device (1) is provided with a yarn passage (10) provided with a yarn introduction section (11) and a yarn ejection section (12); a nozzle (2) having an air injection hole (14) that injects air into the yarn passage (10); and a collision body (4) facing an outlet (12a) positioned at the leading edge of the yarn ejection section (12). The part of the collision body facing the outlet (12a) is formed in a concave shape.</p>
