Abstract: The invention relates an implantable access device for a catheter for supplying an active substance to an active site. The inventive access device comprises a chamber (12) which is arranged in a housing (2) for receiving said active substance and is closed with a piercable membrane (10). A connecting piece (18) to which the catheter is connectable is fluidly connected to the chamber (12). The catheter is fixed by means of two clamps (19, 20) which are fixable to the housing (1) preferably by means of elastic fixing arms (28, 29). The chamber (12) receiving the active substance is embodied in an insertion element (11) which is arranged in the recess (9) of the housing by an intermediate clamping of the intermediate layer of the membrane (10) in such a way that the insertion element produces a pressure force to said membrane.