An endodontic instrument according to an embodiment of the present invention is an instrument for removing a pulp by the rotation of a cutting blade or enlarging a root canal. A cross section perpendicular to a rotary axis from at least a portion of the cutting blade includes: first and second cutting edges positioned on a concentric circle for defining an outermost portion of the cutting blade in the radial direction thereof； first and second guide edges positioned at an inner portion of the concentric circle； a first bending edge positioned at a portion inner than the first guide edge in the radial direction； a second bending edge positioned at a portion inner than the second guide edge in the radial direction； a first connecting part for connecting the first cutting edge with the first guide edge； a second connecting part for connecting the second cutting edge with the second guide edge； a first bending part for connecting the first guide edge with the first bending edge； a second bending part for connecting the second guide edge with the second bending edge； and a flute part for connecting the first cutting edge with the second bending edge. The first cutting edge, the first connecting part, the first guide edge, the first bending part, and the first bending edge are sequentially positioned along the reversed direction of the rotating direction, the second cutting edge, the second connecting part, the second guide edge, the second bending part, and the second bending edge are sequentially positioned along the reversed direction of the rotating direction, and the first guide edge is positioned at a portion inner than the second guide edge in the radial direction.본 발명의 일 실시예에 따른 치내요법 기구는, 절삭날의 회전에 의해 치수를 제거하거나 근관을 확대하는 기구로, 상기 절삭날의 적어도 일부에서의 회전축과 수직인 단면은, 상기 절삭날의 반경 방향 최외측을 규정하고 동심원 상에 위치하는 제1 절삭에지 및 제2 절삭에지, 상기 동심원의 내측에 위치하는 제1 가이드에지 및 제2 가이드에지, 상기 제1 가이드에지보다 반경 방향 내측에 위치하는 제1 절곡에지, 상기 제2 가이드에지보다 반경 방향 내측에 위치하는 제2 절곡에지, 상기 제1 절삭에지와 상기 제1 가이드에지를 연결하는 제1 연결부, 상기 제2
