We use intraoperative spinal cord monitoring in laminoplasty using the Threadwire saw (T-saw). We experienced change of amplitude in 5 cases (3 in Cervical spondylotic myelopathy, 2 in cervical ossification of the posterior longitudinal ligament). Somatosensory evoked potential was used in 3 cases and spinal cord evoked potential in 2. The change of the amplitude occured during inserting the T-saw in four cases and during use in one. In 3 cases, the amplitude recovered at the end of the surgery. There were 3 cases of postoperative neurological deficit. While laminoplasty using T-saw has been generalized for the surgery of cervical spine, there are some cases in which operative procedures cause neural injury. It is important to exercise more care in each procedure to avoid spinal cord damage.