A disc-shaped tool 10 includes a plurality of virtual regions formed such that it is surrounded by two radius lines extending from a rotation center of a disc-shaped base metal 11 and two concentric circles on the base metal disposed around the rotation center. A central angle formed by the two radius lines is equal to or less than 90°, and the number of the virtual regions is 4 to 24. The concentric circle located in a center of an interval of the two concentric circles forming the virtual region is in a range of 0.6 r to 0.8 r with respect to the rotation center of the base metal when a maximum gullet bottom radius of the base metal is r. An overlapping of the virtual regions continuously adjoining each other is in a range of 0° to 12°. A minimum neighborhood distance between the adjoining slits is equal to or more than 0.05 r. A ratio of a length of an arc of the central concentric circle in each virtual region with respect to the interval of the two concentric circles in the virtual region is 3 to 6.