the warp a the velocity of the shuttle 14 is fastest in the step of picking motion in which the shuttle 14 passes through the shed c then in a step for terminating the picking motion the shuttle 14 starts to decelerate from the position where the shuttle 14 has passed through the shed c and stops at the point most distant from the warp a again the shuttle 14 starts to accelerate toward the warp a in the reverse direction in another step for initiating a picking motion by repeating these motions the shuttle 14 successively passes the thread of the weft b between the threads of the warp a as shown in fig5 when the shuttle 14 moves rightward and approaches the warp a causing the tangs 54 inserted into the apertures 72 of the shuttle 14 to approach the position where the elevation of the guide rail 56 is low the tang 54 on the right side goes down and comes out of the aperture 72 thus when the shuttle 14 approaches the warp a the tang 54 on the right side first starts to go down along the guide rail 56 and the tang 54 on the right side is not upwardly projected from the sliding plate 50 below the warp a next when the shuttle 14 is moved farther and the tang 54 on the left side approaches the warp a the tang 54 on the left side also starts to go down and to come out of the aperture 72 at the same time the tang 54 on the right side starts to go upwardly along the guide rail 56 and is inserted into the aperture 72 of the shuttle 14 then when the shuttle 14 is moved.