The invention relates to a tying device of a type comprising: a work surface (10) comprising an opening (11) in the shape of a slot; a tying member (103) which can be activated so as to place at least one string (400) around an item (500) which is moving in a transfer direction (A) on a first side of the work surface (10), and to carry a portion of said string (400) to a second side of the work surface (10), forming at least one loop; and a knotting lip (55) capable of closing the loop with a knot on the second side of the work surface (10). The slot extends generally in the transfer direction (A), allowing a portion of the loop to pass through, but keeping the knot on the second side of the work surface (10) over at least a portion of the movement of the item (500).