To prevent the leaving of a miss-yarn generated by weft-insertion miss in a warp opening of a loom furnished with a weft-selection means to select and position a weft from a waiting position to a weft-insertion position according to a weft-selection pattern.

Information on tensions of wefts Y1-Y4 detected by tension detectors 51-54 is transmitted to a change controlling apparatus C1. The change controlling apparatus C1. judges the presence or absence of the generation of weft-insertion miss based on the weft selection pattern information transmitted from a weft selection controlling apparatus C2, tension information from tension detectors 51-54 and information on the rotation angle of loom obtained from a rotary encoder 32. When a weft-insertion miss is generated, the judging circuit judges the presence or absence of the weft-insertion in the weft following the missed weft based on the detection signals transmitted from the tension detectors 51-54.