To provide a constitution technique for a circular saw contributing to the enhancement of space saving properties.

This cutting tool 101 has a main body part 103 having a blade 113 advanced in a predetermined cutting direction while rotationally driven to cut a material to be processed and the base 151 connected to the main body part 103 to come into contact with the upper surface of the material to be processed. The cutting tool 101 is constituted so as to perform cutting work in such a state that the blade 113 is protruded to the outside of the side surface 152 of the base 151 by tilting the main body part 103 centering around the axial line almost parallel to the cutting direction and the tilted main body part 103 is regulated of the outward protrusion from the side surface 153 on the opposed side of the base 151.