A rotary tool may include a main body having a circular columnar body, including a rotation axis and extending from a first end to a second end. The main body may include first flutes, second flutes, a first cutting edge, and a second cutting edge. The first flutes may have a helix angle θ1 and the second flutes a reverse helix angle θ2. The first cutting edge may be located on a ridge line where the outer periphery of the main body intersects with the first flutes and the second cutting edge at a ridge line where the outer periphery of the main body intersects with the second flutes. The θ2 may be larger than the θ1, m≥5, m−n≥3, and m and n are coprime numbers, where m is the number of the first flutes and n is the number of the second flutes.