The authors present a case of material reaction to suture anchor, which is rarely reported. Leukocyte rate, leukocyte differential, multiple cultures, and gram stain test could not prove infection. A second surgery for exploration of the shoulder joint was performed to reconstruct the rotator cuff without using anchors, and the rotator cuff tear healed after the second surgery. During the second surgery, the bone surrounding the anchors was found to be eroded and substituted with necrotic tissue. The anchors protruded outside the bone. The pathological examination of the necrotic tissue showed multinucleated giant cells of foreign body type, some of which had engulfed minute splinters of particulate foreign material. Either metal- or suture-induced bioreaction is suspected in this case.