PURPOSE: To prevent the formation of defective knots from large and small two loops by specifying the crossing angle of two nipped strings to the inner surface of the movable tine of a knotter bill and the clearance between the movable tine and the fixed tine.

CONSTITUTION: The tip crossing angle θ of the inner surface of a movable tine to a fixed tine and the clearance L between the tips of both the tines are set so that two nipped strings a1, a2 nipped with a knotter bill 7 are arranged with the fixed tine 7a and the movable tine 7b in a string-nipping direction. When released from the knotter bill, the two nipped strings are thereby simultaneously released, thus not producing a difference between the releasing abrasion resistances of the two strings.