A parathyroid carcinoma is a rare cause of primary hyperparathyroidism. Even though the clinical presentation in a parathyroid carcinoma is usually symptomatic and different from that in benign parathyroid disease, a definite diagnosis can be made only by using a histologic examination of local invasion to surrounding tissue or metastases to regional lymph nodes or distant sites. It is important to confirm the malignancy at the initial operation because a radical resection offers the only possibility for cure. We experienced a 62-year-old woman with primary hyperparathyroidism caused by a parathyroid carcinoma, who had revealed the clinical manifestations of acute pancreatitis. A carcinoma in the right lower parathyroid was confirmed by histopathologic findings of invasion to the thyroid capsule. The patient was cured by using a radical resection of the parathyroidal mass, including the right lobe of the thyroid, the surrounding soft tissues, and the regional lymph nodes.