We report a case of a large vesicourethral stone resulting from a long-term indwelling urethral catheter. A 66-year-old man visited our hospital emergency room on October 24, 2006 with a chief complaint of difficult urination. Although a urethral catheter was inserted temporarily based on the diagnosis of the doctor on duty, the patient did not return to our hospital for follow-up examination. On July 10, 2008, he was wheeled into our hospital with symptoms of general fatigue, urinary retention and post-renal failure due to urethral catheter obstruction. The catheter was undisturbed, and computed tomography revealed a large bladder stone that extended along the lines of the catheter. A cystostomy was established, and after renal function had recovered, the bladder stone was completely removed via laparotomy following the transurethral approach. The stone consisted of magnesium ammonium phosphate and calcium phosphate. It was concluded that the stone was closely related to a urinary tract infection caused by a Proteus strain. We discuss this unusual case, which is characterized by the stone size and the clinical course.