Neuroblastoma is the most common extracranial solid tumor in children, and accompanies various clinical symptoms including hypertension. Hypertension is associated with catecholamines secreted from the tumor, and is usually not severe. We report one case of malignant hypertension with cardiac failure in a patient with adrenal neuroblastoma, successfully treated with adrenalectomy. A 3 year-old boy complained of protrusion of the chest wall. Physical examination revealed severe hypertension with cardiac failure. The levels of metabolites of catecholamine were increased in blood (norepinephrine >2000 pg/mL) and urine (norepinephrine 1350.5 ug/day). Abdominal CT showed a 7 cm-sized solid mass arising from the right adrenal gland. After stabilizing the hemodynamics with oral phenoxybenzamine, right adrenalectomy was performed. Pathological diagnosis was a ganglioneuroblastoma. The hypertension and cardiac failure were resolved after tumor removal.