We reported a case of neutropenic enterocolitis (NE) with septic shock during the treatment of acute promyelocytic leukemia (APL). A 42-year-old man, who had been in consolidation therapy for APL, developed fever and right lower abdominal pain. His white blood cell count decreased to 150mm^-3 and he lapsed into septic shock. Under the diagnosis of diffuse peritonitis, emergency laparotomy was done. NE was diagnosed at this time and ileocecal resection was performed. On admission to ICU after the operation he remained septic and critically ill. We performed extracorporeal endotoxin removal (ECER) three times to eliminate endotoxin (ETX) from his bloodstream. His condition improved and ETX concentration was reduced from 81.9pg·ml^-1 to 14.5pg ·ml^-1 after ECER. Severe necrotic inflammation is found on pathological analysis of NE. This is a frequent complication in those who undergo chemotherapy for hematological malignancies. Even now, this disease has a high mortality rate. We conclude that the combination therapy of early removal of the necrotic infectious intestine followed by ECER was effective in preventing septic multiple organ failure.