There are disclosed a method and an apparatus capable of carrying out an accurate weft detection corresponding to the yarn sort of a weft to be inserted and also capable of judging the presence/absence of a defective weft inserting with accuracy. In the method, at least one of judgment conditions used for judging the presence/absence of the defective weft inserting are set in advance with regard to each yarn sort of the weft, and when carrying out the judgment, at least one of judgment conditions corresponding to each yarn sort of the weft to be inserted are selected and the presence/absence of the defective weft inserting is judged by using the selected judgment condition and a signal from a weft detecting device. The apparatus faithfully carries out this method.