A n 81-year-old woman was admitted to our institution. Computed tomography performed before transcatheter aortic valve implantation(TAVI)for aortic stenosis revealed a tumor in the rectum. Lower endoscopy revealed that the tumor was a 60mm submucosal tumor and located 2 cm from the anal verge. Abiopsy revealed the diagnosis to be gastrointestinal stromal tumor(GIST). Although the tumor was located near the anal verge and might have invaded the surrounding organs, neoadjuvant chemotherapy(NAC) with 400mg/day of imatinib was initiated to preserve anal function as requested by the patient and her family. After 3 months, the tumor size decreased by 36.6% and there was a decrease in rate of tumor shrinkage. We performed transanal tumor resection and temporary colostomy. After 6 months, we performed colostomy closure, and the patient has remained recurrence-free and is continuing chemotherapy.