PURPOSE: To provide a weft changer for weft insertion of multi-kind yarn having a good high-speed follow-up characteristic.

CONSTITUTION: A main body 11 of the weft changer 1 of the weft insertion device for at least ≥4 kinds of weft threads in the weft insertion of multi-kind yarn in a projectile loom is formed of aluminum and a slide bar 2a of a weft thread transporting member 2 is made of reinforced plastic consisting of polyether ether ketone and carbon fibers by which the weight thereof is reduced. The main body 11 of the weft changer and a high-degree dynamic servo motor 3 are interconnected by a gear 32 of a toothed belt drive assembly 31 and a shaft 16, by which the device is directly drivably constituted. Further, the main body 11 is provided with a groove part 12 for accepting a guide element made of a wear resistant steel sheet for guiding the reciprocation of the weft thread transporting member 2. The device is so constituted as to prohibit the movement of the weft thread transporting member 2 inoperative of the weft insertion by the cooperation of a lateral side projection 22 of the slide bar 2a for connecting the slide bar 2a to a slider 41 by an accompanying member 42 and an arcuate groove part 29 for guiding the same when the weft changer 1 turns.