Granular cell tumor is found in various organs but is rare in the mediastinum. We report a case of 21-year-old woman with a granular cell tumor in the left upper mediastinum. Chest computed tomography (CT) showed a 30 x 20 mm well circumscribed tumor in the left upper mediastinum. Tumor resection was performed. It was found that the tumor involved the sympathetic nerve. Histopathologically, the tumor consisted of cells with eosinophilic granules and diagnosed as a granular cell tumor.