Superior mediastinal parathyroid adenoma is rare and is not found until growing to a large mass. The parathyroid adenoma is mainly located nearby the anterior neck, so it is frequently misdiagnosed as thyroid cyst. Authors experienced a case of parathyroid adenoma in superior mediastinum who complained of hoarseness and left supraclavicular mass. The radiologic study showed a huge mass in the superior mediastinum which was removed through the transcervical approach to the superior mediastinum and confirmed chief cell type of parathyroid adenoma.