PURPOSE: To variously change the size of stitches formed by an edging yarn, by knotting the edging yarn at an interval of half stitch on both sides of a body net fabric and taking out the edging yarn by a prescribed length in excess using taking out books in knotting at the interval of the half stitch.

CONSTITUTION: An edging yarn 2 is caught and taken out in excess by taking out hooks 26 in forming knots on the edging yarns 2. The edge yarn 2 is loosened by the taken out length and a larger stitch than that of the body net fabric can be formed. The taking out length of the edging yarn 2 is changed by regulating an amplitude of vertical motion of a vertical moving plate 14. The edging yarn 2 is taken out by a prescribed length for half stitch forming the stitch and a larger edging yarn 2 than the stitch of the body net fabric can be taken out.