Urinary obstructions from ureteral calculi are one of the causes of postrenal acute kidney injury (AKI). Here we present a case of AKI caused by a 4 mm ureteral calculus with postobstructive diuresis following the spontaneous passage of the calculus. A 13-year-old girl who underwent nephrectomy for the removal of a neuroblastoma eight years previously, visited our institution because anuria had developed over the preceding five days. The serum creatinine level was elevated at 13.4 mg/dL. Radiological examinations showed the right solitary kidney with moderate hydronephrosis and a 4 mm calculus in the upper right ureter. The patient immediately underwent hemodialysis. After the ureteral calculus was passed spontaneously on day 2 of hospitalization, urinary output increased to more than 5,200 mL per day. Intravenous fluid replacement with careful monitoring of weight, intake, output, and serum and urine electrolytes was performed. On day 5 of hospitalization, the patient's condition stabilized.