Ligamentum flavum hematoma is a rare condition. Twenty cases including present case have been reported in English-language literature. Among them, only one case reported in pure thoracic spine. A 72-year-old man presented with thoracic myelopathy without precedent cause. Magnetic resonance images revealed a posterior semicircular mass which was located in T7 and T8 level compressing the spinal cord dorsally. T7-8 total laminectomy and extirpation of the mass was performed. One month later following surgery, the patient fully recovered to normal state. Pathologic result was confirmed as ligamentum flavum hematoma. Ligamentum flavum hematoma of rigid thoracic spine is a very rare disease entity. Most reported cases were confined to mobile cervical and lumbar spine. Surgeons should be aware that there seems to be another different pathogenesis other than previously reported cases of mobile cervical and lumbar spine.