The case was a woman in her 50s. Total pelvic resection was performed for advanced rectal cancer(cT4b[vagina]N3M0, cStage Ⅲc), after neoadjuvant chemoradiation therapy. Five months after the operation, she was unable to stand due to severe back pain. Spinal MRI revealed multiple bone metastases and lumbar fractures. In addition, dysphagia and dysarthria rapidly progressed almost simultaneously with back pain. Initially, brain metastasis was suspected, but head MRI revealed Collet-Sicard syndrome due to skull base metastasis. Irradiation to the skull base and high cervical spine, thoracolumbar spine was started. After irradiation, her back pain and cranial nerve symptoms improved. She was discharged and received palliative treatment. About a month after discharge, she was hospitalized for recurrent dysphagia and died on day 5 of hospitalization. Collet-Sicard syndrome is caused by damage to the cranial nerves Ⅸ to Ⅻ and is often caused by a tumor. Trauma, vasculitis, and internal carotid artery dissection have been reported as other causes. Symptoms such as hoarseness, dysarthria, tongue atrophy, dysphagia, and headache have been reported. Collet-Sicard syndrome due to bone metastasis of colorectal cancer were very rare, and we found only one other report. We report our case with some literature considerations.