The present authors describe an uncommon case of iatrogenic bladder stone formation in a patient who underwent surgery for pelvic organ prolapse. A female patient who underwent high uterosacral ligament suspension ten years ago presented with pyuria and irritable bladder symptoms that did not respond to treatment. She had not experienced any specific urinary symptoms during the previous ten years. Patient evaluation revealed bladder stone formation on the non-absorbable suture material used during the previous operation. Cystoscopy during the previous operation did not find the suture material, and the suture knot that was tied extravesically during the operation was found inside the bladder. These strongly suggest delayed migration and rotation of the suture knot after surgery rather than direct penetration of the bladder during operation. Delayed suture migration is a long-term complication that clinicians should consider in a patient who suffers from recurrent urinary symptoms after pelvic surgery around the bladder.