A ligating instrument comprising an anvil body and a staple driving body with a longitudinal groove which accommodates a staple magazine with staple pushers and a wedge. The latter is mounted on a carriage arranged in guides provided on the lateral walls of the staple driving body. The instrument incorporates a device for adjusting the ligation spacing, which comprises a stationary axle mounted on the carriage transversely to the latter. The tapered portion of the wedge is fitted on this axle. The ligation spacing adjustment means also includes a movable support articulated to the wedge in its rear portion so that the movable support and the wedge can be set in motion at a perpendicular to the guides of the carriage.