We report a case of schwannoma arising from brachial plexus with intrathoracic extension. An 18-year-old man demonstrated a tumor shadow at the right pulmonary apex area. In the 2-months of follow-up, tumor size had been growing rapidly. Chest computed tomography (CT) and magnetic resonance imaging (MRI) revealed a giant tumor mass infiltrated right lung. We perfomed operation under the posterolateral incision approach. The pathological diagnosis was schwannoma. We resected this tumor safely and conserved with the seventh, eighth cervical nerve of the brachial plexus under posterolateral incision approach.