To make an automatically lacing and knotting device compact as a whole by minimizing the occupying space of a device making up a lacing/knotting part under a table.

A needle bar (5) with a needle (6) mounted on at its tip is so arranged at one end part of an arm (3) as to be movable vertically and parallel sideways. A thread selvedge bar (13) is so arranged across a pair of loopers (11) and (12) disposed under a throat plate (10) and the undersurface of the throat plate (10) as to move one of threads (T) positioned respectively on the surface sides facing each other of first and second loopers (11) and (12) to the side of the other thread, a thread knotting mechanism (14) is so arranged between the thread selvedge bar (13) and the pair of loopers (11) and (12) as to let its tip part plunge between them and a thread cutting knife (15) is so mounted into the thread knotting mechanism (14) as to be movable forward or backward. A thread tightening bar (16) is so arranged as to be movable forward or backward relative to a thread ring formed at the tip part of the thread knotting mechanism (14) and a second thread cutting knife (17) is so arranged under the throat plate (10) as to be movable forward and backward along the throat plate.