A 58-year old man was admitted to our hospital complaining of right back pain, fever, abdominal fullness and epigastralgia. Chest CT revealed a mass shadow in the right S6 together with destruction of the thoracic vertebrae. These findings suggested lung cancer and its spinal invasion. A transbronchial lung biopsy specimen showed inflammatory lymphocyte infiltration. MRI T2 image of the spine showed a high intensity at the Th7/8 disc space, suggesting pyogenic spondylitis. After broad-spectrum antibiotics including PAMP/BP and CLDM were administered, both the spinal lesion and the pulmonary lesion improved gradually. The clinical course suggested that the pulmonary inflammatory lesion had spread from pyogenic spondylitis. In our case, the pyogenic spondylitis was mimicking a spinal invasion of lung cancer. In addition, MRI is thought to be useful for diagnosing spinal lesions.