An organ-fixing instrument and a gastric fistula catheter able to accomplish proper suturing reliably and through a simple procedure. An organ-fixing instrument 10 is structured by a transversely elastic, cylindrical sheath 12, and a body surface installation part 11 attached to the base part of the sheath 12. In the body surface installation part 11 there are provided a through-hole 13 communicating with the sheath 12 and a pair of needle through-holes 14, 15. The sheath 12 is structured by a web-shaped covering part 16 made from a resin, a plurality of reinforcing parts 17 provided at the base end portion of the covering part 16, and skeletal parts 18a, 18b provided at the tip portion of the covering part 16. A suturing thread catch 18 projected in an axial direction by compression in the axial direction is structured by the tip side portion of the covering part 16 and the skeletal parts 18a, 18b.
