A needle holder for holding a curved needle to which a suture thread is connected. The needle holder includes a flexible tube; and a grasper provided at a distal end of the flexible tube. The grasper includes a first jaw having a groove, and a protrusion at a distal end portion of the first jaw; and a second jaw movably connected to the first jaw. The grasper can hold the curved needle between the second jaw and the protrusion of the first jaw, and can hold a part of the suture thread between a surface of the groove and the second jaw such that another part of the suture thread passes through a gap formed between another surface of the groove and the second jaw. The protrusion has a hook surface for hooking the suture thread extending outside the groove.