A study was carried out to obtain the adequate CT picture of thoracic spinal canal using a cadaver vertebra. EMI CT 5005 scanner was used and 13mm thick slice of cadaver vertebra was obtained. After obtaining of CT picture, we made a same thick specimen of cadaver vertebra and compared CT picture to softex x-ray picture. The best condition of thoracic spinal canal by CT showed nearly 400 EMI units in window width and 150 in level. Scanning angle of thoracic spinal cannal was permitted within 10° in mesurement and in configuration. The precise location of being scanned was known by using different lengh of radiopaque catheter markers taped on a patient's back and comparing CT pictures to x-ray picture. Normal thoracic spinal canal was examined and we observed normal thoracic spinal configurations and confirmed that the ratio of frontal diameter to sagittal diameter had a pattern.