To provide a weft-controlling apparatus capable of accurately and easily controlling the delivery length a weft.

This weft-controlling apparatus in loom is provided with a weft length measuring apparatus 1 composed of a length-measuring roller 1a and a pinch roller 1b, a weft delivery apparatus composed of a gripper and a nozzle 3 and weft-arrival sensors 6, 7 placed at the weft-arrival positions of the loom. The controlling apparatus is operated by a process to store the measured time of a weft determined by the weft arrival sensor, a step to calculate the average arrival time of weft over a definite number of picks, a process to compare the average arrival value with a preset standard target value and a process to control the weft length measuring apparatus based on the comparison result obtained by the former process.