A tissue-fastening tool indwelling device includes: a sheath in which a lumen is formed； a needle tube having a needle tip, formed in a tubular shape, and disposed to be retractable from a distal end of the lumen； a tissue-fastening tool having a restoring force for restoration to a curved shape with distal and proximal end side regions and disposed inside the needle tube in a stretched state； and a stylet coupled to a proximal end portion of the tissue-fastening tool in the needle tube. The stylet has a first state in which the stylet is advanced straight with respect to the needle tube and the sheath until the entire distal end side region of the tissue-fastening tool protrudes from the needle tube, and a second state in which the stylet is advanced while being rotated until a proximal end of the proximal end side region of the tissue-fastening tool protrudes from the needle tube.
