The mechanism of spinal deformity after surgical removal of a cervical spinal cord tumor or tumorous lesions was studied in 36 patients, based on the spinal functional curve prepared from the intersectional angle. The postoperative spinal deformity depends on the surgical level and the type of operation. In the laminectomy group, kyphosis of the upper cervical spine and compensatory increased lordosis of the lower cervical spine were observed in the C2 laminectomy patients. Localized kyphosis of the spine at the cervicothoracic junction and compensatory increased lordosis of the upper cervical vertebrae were noted in the C7 laminectomy patients. In the laminoplasty group, spinal deformities were less frequently observed, and when present the deformity was limited to a slight increase of lordosis, even in patients who had the facetectomy. These facts demonstrate the preventive effect of the laminoplasty regarding postoperative spinal deformity. Laminoplasty with reconstruction of the erector spinal muscles and the nuchal ligament is recommended for patients with a spinal cord tumor or a tumorous lesion. The spinal functional curve was significant in studying the biomechanics of the vertebral column with the advantage that both alignment and mobility of the spine are simultaneously, respectively and precisely visualized.