A retroodontoid pseudotumor is a nonneoplastic mass arising posterior to the odontoid process. We describe a 67-year-old woman admitted to our hospital with numbness of the left upper extremity, dysbasia, and impairment of fine motor movement of the fingers. She was diagnosed with myelopathy due to a retroodontoid pseudotumor underlying rheumatoid arthritis. According to previously published reports, reduction of the pseudotumor was achieved by posterior fusion alone. However, in the present report, the tumor was very large, and there was no instability at the atlantoaxial segment. Therefore we managed the patient by resection of the mass through a high lateral cervical approach without fusion. The spinal cord symptoms diminished rapidly.