Abstract: A rotary diamond dresser, with a V-groove circumferentially formed around a heavily abraded high load part of the circumference of a circular dressing body. A plurality of octahedral diamond grains are sequentially set along the V-groove of the circular dressing body such that the oriented crystal surfaces of each diamond grain are bonded to the respective surfaces of the V-groove. A plurality of small-sized diamond grains, other than the octahedral diamond grains, are secured to the surface of the circumference of the dressing body, other than the high load part. The oriented crystal surfaces of the octahedral diamond grains and the small-sized diamond grains are formed to make respective contact surfaces that contact and dress a grinding wheel. Thus, the rotary diamond dresser, which is easily produced, has excellent abrasion resistance, and is low-priced.