We report a 49-year-old man with alcoholic severe acute pancreatitis (SAP) complicated by drug-induced acute tubulointerstitial nephritis (DI-AIN). Oliguria persisted and became anuric again on day 17 despite improvement of pancreatitis. He presented rash, fever and eosinophilia from day 20. Renal biopsy was performed for dialysis-dependent acute kidney injury (AKI), DI-AIN was revealed, and prompt use of corticosteroids fully restored his renal function. This diagnosis might be missed because it is difficult to perform renal biopsy in such a clinical situation. If the patient's general condition allows, renal biopsy should be performed and reversible AKI must be distinguished from many cases of irreversible AKI complicated by SAP. This is the first report of biopsy-proven DI-AIN associated with SAP, suggesting the importance of biopsy for distinguishing DI-AIN in persisting AKI of SAP.