Lymph node metastasis of thyroid cancer occurs to anterior compartment (level VI) and superior mediastinal lymph node (Level VII). In lateral neck, it occurs commonly in middle and lower jugular lymph node (level III, IV). And it can also metastasis to posterior neck lymph node (level V). Superior mediastinal lymph node metastasis of thyroid cancer requires superior mediastinal dissection with massive removal of peritracheal and periesophageal soft tissue. After superior mediastinal dissection, severe complication may occurs such as innominate artery rupture and tracheal necrosis. We describe a case of tracheal necrosis as a complication of superior mediastinal dissection and total thyroidectomy in thyroid cancer patient.