The invention provides a closure device (1) for sealing an incision channel leading through a vessel wall and into the vessel. The closure device (1) comprises a haemostatic material (3), which is contained in the distal end of an elongated insertion assembly (2). The insertion assembly (2), which comprises a stationary part (4) and a retractable part (5) being slidably movable with regard to each other, is adapted to be attached to an introducer (7) being in position in the incision channel, so that the insertion assembly (2) can be slid along the introducer (7) until the distal end of the insertion assembly (2) is in contact with the vessel wall, where the haemostatic material (3) is delivered in the incision channel by a retracting movement of the retractable part (5).