Mediastinal granular cell tumor is rare. We report a case of 16-year-old woman with a granular cell tumor in the right upper-middle mediastinum. Chest computed tomography (CT) and magnetic resonance imaging (MRI) revealed a 4.0 x 2.5 x 5.5 cm well circumscribed mass in the right upper-middle mediastinum. Tumor resection was performed. It was found that the tumor involved right vagus nerve. The tumor was completely excised with combined resection of the right vagus nerve peripheral to the right recurrent nerve. Histopathologically, the tumor consisted of round to polygonal cells with abundant eosinophilic granular cytoplasm, and diagnosed a granular cell tumor.