The purpose of this study was to examine the effects of the thoracic spine manipulation on spinal alignment (Cobb angle), pain, and trunk range of motion (ROM) in a patient with mild thoracic scoliosis. The Cobb angle was 11.0° and there was a right deviation of the thoracic spine. The subject had thoracic and lumbar pain, and had felt stiffness during turning of the trunk for about 3 years. Thoracic manipulation was applied at the upper thoracic spine as a therapeutic intervention three times per week for 5 weeks. After intervention, the Cobb angle decreased from 11.0° to 5.5° and the pain score decreased from 4.0 to 1.5, and the trunk left rotation ROM increased from 30.0° to 41.5°, and trunk right rotation ROM increased from 26.0° to 39.0°. These results suggest that the thrust thoracic manipulation technique had a positive effect on the spinal alignment, pain and trunk rotation ROM in patients with mild scoliosis.