The patient was a 21-year-old male. He presented with right lower abdominal pain and showed tenderness in the same area. An abdominal contrast-enhanced CT examination revealed a 45 mm tumor that continuously stained in the right transverse colon. The patient presented with tenderness and rebound tenderness. Due to a suspected submucosal tumor, laparotomy was performed and an elastic hard tumor of 5 cm in size was found on the serous membrane side of the right transverse colon. As malignancy could not be ruled out, a right hemicolectomy with lymph node dissection was performed. The pathological diagnosis was an inflammatory myofibroblastic tumor(IMT), characterized by the proliferation of spindle- shaped spindle-shaped fibroblast-like cells with inflammatory cell infiltration. As of 9 years post-surgery, there has been no recurrence. However, long-term surveillance is necessary.