A 65-year-old man was referred to our hospital with a chief complaint of hyperglycemia. Computed tomography showed left clear-bordered adrenal mass. The serum aldosterone/renin ratio was elevated, and the low-dose dexamethasone suppression test revealed no suppression of serum cortisol. Adrenal venous samplingdemonstrated excess secretion of cortisol from the left adrenal gland, and excess secretion of aldosterone from bilateral adrenal glands. Laparoscopic left partial adrenalectomy for primary aldosteronism combined with Cushing's syndrome was performed. The result was insulin withdrawal and the reduction of antihypertensive drugs.