Rhino-orbito-cerebral mucormycosis (ROCM) is an uncommon, acute, and aggressive fungal infection occurring in several immunocompromised states including poorly controlled diabetes. ROCM causes a very high residual morbidity and mortality due to the angioinvasion property of the fungus. Acromegaly is a chronic condition resulting from the excessive secretion of growth hormone, generally from pituitary adenoma. Although it has been demonstrated that acromegalic patients have an increased risk of neoplasm, gastric cancer with acromegaly is very rare. We experienced a case of pituitary mucormycosis in the diabetic patient with acromegaly and gastric cancer. The patient was treated successfully with subtotal gastrectomy for early gastric cancer, transsphenoidal surgery for pituitary adenoma, and a systemic application of amphotericin B for the mucormycosis.