A 40-year-old man presented with a sudden severe headache and complete right-sided ptosis. Neuro-ophthalmic examination revealed a right oculomotor nerve palsy. Computed tomography of the brain showed a round isodense intrasellar mass. Magnetic resonance imaging demonstrated a pituitary tumor with some areas of infarction and invasion into the right cavernous sinus, which was diagnosed as pituitary apoplexy. The patient received intravenous steroid for 10 days with no recovery of the oculomotor nerve palsy. He underwent trans-sphenoid tumor resection followed by complete recovery of the oculomotor nerve and no sign of tumor in postoperative MRI, two weeks after the surgery.