A 70-year-old man visited the Department of Head and Neck Surgery with a chief complaint of dysphagia. A tumor was observed in the epiglottis and vocal cord, and was diagnosed as squamous cell carcinoma by biopsy. Computed tomography (CT) showed a tumor mainly in the vocal cord. CT scans revealed a tumor centered on the vocal cord, with bilateral cervical lymph node metastases and a well-circumscribed 20-mm tumor in the anterior mediastinum. Fluorodeoxyglucose-positron emission tomography (FDG-PET) showed uptake in the primary lesion, left cervical lymph nodes, and anterior mediastinal tumor, which suggested a lymph node metastasis but did not exclude thymoma. The patient underwent video-assisted thoracic surgery (VATS) resection of the anterior mediastinal tumor with total laryngectomy, total thyroidectomy, and bilateral cervical lymph node dissection. The final pathological diagnosis was laryngeal cancer (glottic cancer, pT4aN2M1, pStage IVC) with thymic metastasis (presenting as an anterior mediastinal tumor). Thymic metastasis of laryngeal cancer is rare, and appears difficult to preoperatively differentiate from other mediastinal tumors.