We report a case of a rupture of the common carotid artery caused by the medication of lenvatinib. The patient, 70-yearold female, was referred to our hospital by unresectable papillary thyroid cancer infiltrated the left common carotid artery. Externalbeam radiotherapy and radioiodine therapy were undergone after totalthyroidectomy. After 1 year 7 months from operation, she admitted our hospital due to left shoulder pain and dysphagia caused by the growing left cervical tumor. The medication of lenvatinib was decided after the careful informed consent. Computed tomography on the eighth day of lenvatinib medication showed the existence of air infiltration into the tumor surrounded left common carotid artery. So, a discontinuance of lenvatinib medication was decided immediately. But, on the ninth day, a rupture of the left common carotid artery occurred and on the tenth day, she died. Lenvatinib medication for the patient with the tumor surrounded artery should be decided carefully.