The invention relates to a device for the implantation of microcoils (3, 7, 11, 12) into body cavities and blood vessels, in particular aneurysms, with said microcoils (3, 7, 11, 12) comprising wires forming a plurality of windings (4), at least one microcoil serving as occlusion helix (3) for the occlusion of the body cavity or blood vessel, and the device consisting of a catheter, one or several microcoils (3, 7, 11, 12) movably arranged in longitudinal direction within the catheter and at least one securing means (10) passing at least partially through the lumen (9) of the occlusion helix (3), with said securing means (10) being fixed in its end areas inside the microcoils (3, 7, 11, 12). Such a fixation of the securing means (10) is achieved in at least one end area by providing a frictional connection with the microcoil (3, 7, 11, 12) in such a manner that this connection is detachable from the microcoil (3, 7, 11, 12) when a certain tensile force acting on the securing means (10) is exceeded. In this way, a sudden breakage of the securing means (10) is avoided if too high a pull force is applied so that forces otherwise liberated cannot destroy the occlusion helix (3) or cause other damage in the blood vessel.