We experienced anesthetic management during pancreatectomy in a pediatric patient with congenital hyperinsulinemia. The patient was 6 months of age, measured 65.2 cm in length (-1.2SD), and weighed 10.6 kg (+3.2SD). His blood sugar was 24 mg/dL at birth, so he received an insulin secretion suppressant and dextrose. However, blood sugar management was difficult and hypoglycemia occurred. During pancreatectomy, anesthesia was maintained with oxygen, air, sevoflurane, fentanyl, and remifentanil. Dextrose administration was regulated and ranged from 7 mg/kg/min to 1 mg/kg/min based on blood sugar measurement. The patient's blood sugar rose to a maximum of 300 mg/dL but gradually decreased with insulin administration, stabilizing at 150 mg/dL. Hypoglycemia did not occur intraoperatively. We were able to achieve blood sugar stability with appropriate dextrose administration. Because blood insulin concentration changes dramatically during pancreatectomy for congenital hyperinsulinemia, frequent blood sugar measurement and dextrose infusion adjustment are required during anesthesia.