Provided is a dental file exhibiting high performance and having high flexibility and excellent root canal followability. A dental file (10) of the present invention includes a working portion (11) in a spiral shape. An outer edge of the sectional shape of the working portion (11) at any position includes a single arc (40) and three or more lines (41, 42, 43). One end of the arc (40) forms a first cutting blade. The three or more lines (41, 42, 43) are positioned inside a virtual circle (50) partially including the arc (40). The length of the arc (40) may be equal to or greater than 1/12 and equal to or less than ⅓ of the circumferential length of the virtual circle (50), or a second cutting blade (16) may be further provided inside the virtual circle (50).