Schwannomas are rarely seen in the nose and paranasal sinuses, and very rarely originate from the nasal septum. Moreover, a rapidly growing schwannoma suggests a possible malignant change, as these tumors are usually benign and slow-growing. Herein, we report a case of schwannoma originating from the nasal septum that rapidly increased in size. An 83-year-old female patient presented to our hospital with a 2-month history of nasal obstruction. CT revealed a soft tissue mass occupying the entire right nasal cavity. Histopathological examination of a biopsy specimen revealed that the tumor was a schwannoma. Both the patient and her family refused surgical intervention as she was elderly and also suffered from dementia. Therefore, we adopted a wait-and-watch approach. The patient subsequently complained of worsening nasal obstruction and the tumor was observed to have grown rapidly during the 1-year observation period. CT showed that the tumor had extended into the left nasal cavity and right ethmoidal sinus. Given the rapid enlargement within this short period of time, we again recommended surgery due to the possibility of malignant transformation of the tumor, and the patient and her family agreed to surgical intervention. Endoscopic sinus surgery was performed under the guidance of a navigation system. The origin of the tumor was located in the posterior portion of the nasal septum and we were able to remove the tumor completely. The resected tumor was diagnosed as a schwannoma based on positive immunohistochemical staining for anti-S-100 antibody. There was no evidence of malignant transformation, and the patient did not develop any tumor recurrence or metastasis after the surgery.