The present case involves a 56-year-old woman with Cushing’s disease due to pituitary macroadenoma. The patient had suffered from central obesity, general weakness for 1 year. Her serum cortisol levels were elevated throughout the observation period and the dexamethasone test failed to suppress the cortisol secretion. Plasma adrenocorticotropic hormone (ACTH) levels were significantly elevated (386 pg/mL). Sellar magnetic resonance imaging revealed a 3.1-cm pituitary tumor occupying the sellar region with extension to parasellar area. The pituitary mass was removed by transsphenoidal surgery incompletely and was pathologically identified as compatible to ACTH-producing pituitary adenoma by immunohistochemistry. Thereafter, cabergoline (1 mg/wk) was administered for the remnant adenoma, which gradually reduced ACTH levels in 7 days before starting radiation therapy. This case demonstrates the efficacy of cabergoline to treat Cushing’s disease caused by pituitary macroadenoma.