The present invention relates to an occlusion device consisting of a braiding ( 2 ) of thin wires or threads ( 4 ) which is given a suitable form in a molding and heat treatment procedure. The occlusion device ( 1 ) has a proximal retention area ( 6 ) and a distal retention area ( 8 ), whereby the ends of the wires or threads ( 4 ) converge into a holder ( 5 ) in distal retention area ( 8 ). A cylindrical crosspiece ( 10 ) is furthermore disposed between the proximal and distal retention areas ( 6, 8 ). With the objective of providing an occlusion device which positions as flat as possible against the septum at the proximal side of a septal defect in the inserted state, the invention provides for the proximal retention area ( 6 ) of the braiding ( 2 ) to exhibit a completely closed proximal wall ( 112 ) disposed with a continuous surface at the proximal end of the occlusion device ( 1 ) which forms the proximal end ( 12 ) of said occlusion device ( 1 ).
