To provide a technique for cutting various workpieces of different external sizes with different outside diameters or the like at the satisfactory cutting accuracy even by the same sawing machine.

In the circular sawing machine that has a cutting blade 1, a drive shaft 2 for the cutting blade 1, and a back cutting blade guide 4 and a front cutting blade guide 5 to guide both sides of the cutting blade 1, each of the front and back cutting blade guides 4 and 5 has at least one contact face 6 that comes into contact with respective sides of the cutting blade 1. The front cutting blade guide 5 is structured to be able to separate or swingablly move backward from the cutting blade 1. The radial distance between the contact face 6 and the drive shaft 2 of the front and back cutting blade guides 4 and 5 is adjustable so that the contact face 6 can come to a predetermined position even if the diameter of the cutting blade 1 differs.