A patient temporally presented Horner's syndrome after a video-assisted thoracoscopic wedge resection of the lung for left pneumothorax is experienced. The patient was admitted to the hospital because of left chest pain, and was operated on with the diagnosis of left spontaneous pneumothorax. At operation, freeing of adhesions and electrocoagulation were needed at the apical chest wall. Horner's syndrome occurred after the operation but improved gradually. Careful manipulation is needed for pleura parietalis near the sympathetic nervous system.