To provide a yarn-threading device capable of surely threading the yarn into a yarn feeding path without deteriorating quality of the yarn.

This yarn threading device S is composed of a head part S1, a compressed air-injecting part S2, and a space part A which is positioned between both of the above parts and opened to the outside, wherein a hollow guide 13, plural guide plates 14a, 14b, 14c which are arranged at predetermined intervals and have yarn inserting-openings 14a', 14b', 14c', respectively, interval- ensuring cylinders 15, and a connecting disc 19 are integrally formed, for example, by aluminum die casting.