Bacterial meningitis is an uncommon complication of pituitary macroadenoma. Bacterial meningitis can occur in patients with pituitary macroadenoma who have received sphenoidal surgery or had cerebrospinal fluid (CSF) rhinorrhea. A 62-year-old male visited our hospital for headache and fever. Brain magnetic resonance imaging showed a pituitary macroadenoma. CSF study revealed acute bacterial meningitis. Intravenous antibiotics and hydrocortisone replacement therapy were started, and lead to good clinical outcome. Bacterial meningitis should be considered in patients with a pituitary macroadenoma who present with meningitis symptoms, even though in the absence of rhinorrhea or surgical history.