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 which is arranged in a housing for receiving the active substance and is closed with a piercable membrane. A connecting piece, to which the catheter is connectable, is fluidly connected to the chamber. The catheter is fixed by clamps that are fixable to the housing preferably by means of elastic fixing arms. The chamber receiving the active substance is embodied in an insertion element that is arranged in a recess of the housing by an intermediate clamping of the intermediate layer of the membrane in such a way that the insertion element produces a pressure force to said membrane.