Urinoma, defined as the urine leakage beyond the urinary tract, is commonly induced by blunt trauma or urinary tract obstruction by stone, intra-abdominal malignancy, or retroperitoneal fibrosis. Spontaneous urinoma is rare and parenchymal pathologic change is rarely mentioned when urinoma is found. We present a case of a 28-year-old man with left flank pain due to spontaneous non obstructive urinoma. The patient received analgesics for flank pain and was found to have bilateral peri-renal urinoma on CT. After discontinuing the medication, urinoma subsided, and the patient was discharged with normal serum creatinine. This was the first case of urinoma induced by NSAID. Its pathophysiology and management of spontaneous urinoma are discussed.