A suture instrument according to the present invention includes a suture tool having an anchor anchored to a biological tissue, a suture thread drawn out of the anchor, and a stopper disposed on the suture thread; a hollow puncture needle, which can house the anchor thereinside, having a hard needle portion formed with an opening at the distal end thereof; a pusher which is disposed to advance and retreat in the puncture needle and a proximal side of which extends to a proximal side with its distal end being in contact with the anchor; and an outer sheath which houses the puncture needle so as to advance and retreat, in which an engaging portion, which is detachably engaged with the suture thread which is drawn in a state where the anchor is housed in the puncture needle, is disposed in the puncture needle or in the pusher.