To realize the excellent cutting ability by setting the diameter and the rake angle to the prescribed values, and making a cutting blade sufficiently bite into a work.

A circular saw 1 is 300-500mm in diameter. About forty base pieces 3 are formed on the outer circumferential part of a circular saw body 2 of the circular saw 1. A cutting blade 5 of cermet tip is implanted in each base piece 3. The projection of each cutting blade 5 from the highest part 7 of the base piece 3 is set to 0.25-0.5mm. The rake angle θ of the cutting blade 5 is set to -3°-+7°. Because the cutting blade 5 is projected in the circular saw 1, the cutting ability is not deteriorated. The circular saw has excellent characteristics of keeping the excellent cutting ability immediately before the saw is completely out of use.