A needle holder includes: a flexible sheath portion which is capable of being inserted into an instrument channel of a flexible endoscope; a first grasping member which is rotatably coupled with a distal end portion of the flexible sheath portion; and a second grasping member which is provided in the distal end portion of the flexible sheath portion. In a state where a curved needle is grasped by a first grasping surface of the first grasping member and a second grasping surface of the second grasping member, the second grasping surface inclines such that a grasped region of the curved needle that is grasped by the first grasping surface and the second grasping surface is positioned between a distal end of the second grasping member and a needle tip of the curved needle in a direction of a center axis of the second grasping member.