A 61 year-old man complaining of asymptomatic gross hematuria was admitted to our hospital in May 2005. Transurethral resection of bladder tumor (TUR-BT) was performed for a bladder tumor (urothelial carcinoma (UC), pTa, G2). The TUR-BT was performed again because cystoscopy revealed a nonpapillary bladder tumor on the posterior bladder wall in September 2007. The pathological findings showed a UC, pTa, G2 and an inflammatory myofibroblastic tumor (IMT), pT1. The TUR-BT was performed two more times for tumor recurrences. We considered a total cystectomy because of the possibility of a pathologically low grade sarcoma and the considerable enlargement of the tumor size for a month after the TUR-BT. Ultimately, a malignant sarcoma was not diagnosed from the pathological findings. We practiced conservative therapy with a steroid and the tumor was reduced.