The present invention relates to an occlusion instrument (1) made up of a braid (2) of thin wires or filaments (4), which obtains a suitable shape by means of a shaping and heat treament method. The occlusion instrument (1) has a proximal retention area (6) and a distal retention area (8), the ends of the wires or filaments (4) running together in a holder (5) in the distal retention area (8). Moreover, a cylindrical web (10) is provided between the proximal and distal retention areas (6, 8). With the aim of making available an occlusion instrument which, in the inserted state, lies as flat as possible on the proximal face of a septum defect, the invention proposes that the proximal retention area (6) of the braid (2) at the proximal end of the occlusion instrument (1) has a completely closed proximal wall (112) with a continuous surface area that forms the proximal end (12) of the occlusion instrument (1).
