Provided is a formed rotary dresser that has regions in which diamond abrasive grains are scattered and arranged on an outer circumferential surface thereof brought into contact with a grindstone, and slit regions in which the diamond abrasive grains are not arranged on the outer circumferential surface thereof. The plurality of slit regions are provided to be inclined with respect to a rotational axis. A plurality of octahedral diamond abrasive grains are arranged along downstream edges of the slit regions in a rotating direction such that any face of an octahedron is parallel with the outer circumferential surface.