A braking band of a disk brake disk has a first plate and a second plate arranged joined to each other by connecting elements. The first and second plates have first and second plate outer surfaces, opposite portions of the first and second outer surfaces forming opposite braking surfaces. The braking band has a plurality of attachment portions for connecting the braking band to a vehicle hub or a bell. Each attachment portion has a connection seat. The attachment portions are spaced by recesses. Each attachment portion has an attachment portion wall having opposite side wall portions, two bottom wall portions and an inner end wall portion, and opposite first and second attachment portion surfaces. Each recess extends radially beyond the connection seat. Each side wall portion is joined to the adjoining bottom wall portion by a cylindrical bottom arch avoiding edges. Each side wall portion is joined to the adjoining inner end wall portion by a cylindrical end arch avoiding edges. Each first attachment portion surface is coplanar to the first braking surface except for the wear of the first braking surface.