A rare case of intrathoracic meningocele associated with neurofibromatosis was reported. A 47-year-old female was admitted to our institute because of an abnormal shadow on chest X-ray. The chest X-ray film showed homogenous opacity with a well defined margin in the right apex. Chest CT showed an enlarged intervertebral foramen and defect of the vertebral arch around the tumor. There was no scoliosis. Though preoperative diagnosis was dumbbell type neurinoma, the tumor was found to be a protrusion of dura mater with spinal fluid out of the spinal canal, covered by thickening tumorous tissue. Part of the wall was excised and the residual opening was carefully repaired and wrapped by the pedicled parietal pleura. Retrospectively, MRI showed characteristic findings of intrathoracic meningocele. The tumorous part of it was diagnosed as neurofibroma on histological examination.