Schwannoma is a rare benign neurogenic tumor arising from the Schwann cells of peripheral nerves. A 77-year-old man presented with progressively worsening left nasal block and hyposmia for the past six months. Nasal endoscopy revealed a polypoidal reddish mass occupying the left middle meatus. The biopsy was in favor of ancient schwannoma. Endoscopic transnasal excision of the mass arising from the left nasal septum was performed. A middle meatal antrostomy was also performed. The tumor cells were positive for S100 protein. Presenting symptoms are common to other sinonasal tumors, and the differential diagnoses include carcinoma, inverted papilloma, sarcoma, lymphoma, and neurofibroma. Schwannomas are composed of spindle cells with two histologically distinct patterns that can be mixed: Antoni type A and Antoni type B. A neural crest marker antigen, S-100 protein, is useful to corroborate our diagnosis. It is vital to consider nasal septal schwannoma in the differential diagnosis of patients complaining of unilateral nasal obstruction with polypoidal nasal mass, especially the posterior third of the nasal septum. Transnasal endoscopic surgery is the preferred approach for nasal septal schwannoma.