A case of nodular fasciitis which arose from the buccal submucosal region is reported. One week after an incisional biopsy, the lesion enlarged alarmingly and protruded from the submucosa. Although a sarcoma was suspected because of rapid growth, the diagnosis of the biopsy was nodular fasciitis showing a haphazard arrangement of plump fibroblasts without atypical mitoses. After complete resection, no signs of recurrence were seen.