To provide a machining blade, a cutting and machining apparatus, and a groove formation tool, which form a groove part linearly not affected by the unevenness of the decorative surface, while preventing a part of the decorative surface of an external panel from getting chipped.

This cutting and machining apparatus 10 has an apparatus main body 11 with a base 12, a rotary shaft 14 protruding from the side part 13 of the apparatus main body 11, and a cutter 15 and a machining blade attached to the rotary spindle 14. The machining cutter 16 is a rotary cutter attached to the rotary spindle 14 and equipped with a cutting edge 27 and a scribing edge 28 to make a linear score. Concretely, the machining cutter 16 has a machining cutter main body 29 formed in a disk shape, the circumferential periphery 29A of which is formed in a serrated shape, where the machining edge 27 and the scribing edge 28 are alternately disposed along the peripheral direction at the edge part of the serrated periphery 29A.