The patient was a 68-year-old man who underwent Hartmann's procedure for a fistula due to rectal cancer in August 2012. The cancer was tub2>tub1, pSE, pN2, pH2, pM1(intrapulmonary metastasis), stage IV. The patient received 5 courses of FOLFOX and bevacizumab as adjuvant chemotherapy. In December 2012, the patient was seen by Otolaryngology for hoarseness. A neck examination revealed induration of the left lobe of the thyroid, and FNA biopsy strongly suggested metastasis of rectal cancer to the thyroid. FDG-PET was performed and revealed extensive accumulation of FDG at the same site. The patient was diagnosed with thyroid metastasis of rectal cancer and underwent a left thyroid lobectomy and lymph node dissection in January 2013. Histopathology confirmed the thyroid metastasis of rectal cancer. Thyroid metastasis of rectal cancer is extremely rare: there are 11 such cases in the Japanese literature, including the case encountered by the current authors. This case is reported here, along with a discussion of some of the literature.