Dental root canal treatment instrument

The invention provides a dental root canal treatment instrument, which can improve the flexibility, the machinability and/or the fracture resistance of the dental root canal treatment instrument. In a dental root canal treatment instrument (100), the cross-sectional shape at a first longitudinal direction position on the tip side is configured from an arcuate part (111) and first linear parts (112), and the number of linear parts constituting the cross-sectional shape closer to the base end side than the tip side is formed so as to increase. 本发明提供牙科用根管治疗器具，提高牙科用根管治疗器具的柔性、切削性和/或抗断裂性。在牙科用根管治疗器具(100)中，末端部侧的第一长边方向位置处的横截面形状由圆弧状部(111)和第一线状部(112)构成，并且构成比所述末端部更靠基端部侧的截面形状的线状部的数量形成为增加。