[Object] To provide a tubular medical treatment instrument indwelling device capable of inhibiting the damaging of a blood vessel or the freeing of parietal thrombus/parietal atheroma from occurring. [Solution means] A tubular medical treatment instrument indwelling device (1) for indwelling a stent graft (SG) expandable in the radial direction, comprising a tubular sheath (10), a rod member (30) that is so constituted as to move forward and backward inside the sheath (10) along the axial direction of the sheath, and a front tip (40) that is provided in the forward end portion of the rod member (30) and has, formed therein, an engaging portion (42) being engageable with an engagement portion (H) provided in the stent graft (SG), the engaging portion (42) being formed in a position where it is hided inside the sheath (10) when the forward end portion of the sheath (10) is sealed with the front tip (40).
