To increase overall operation rate of looms in a weaving factory by dispersing the period of suspension of plural looms.

The method of this invention is to add up the period of passage (t) from the storing point of a prescribed period (T), to count the recurrence number (n) of times of weft insertion defect signals since the starting point and to control the output the signal (St) for stopping weft insertion in a loom based on the period of passage (t) when each weft insertion defect signals is made and the recurrence number (n) of times of weft insertion defect signals.