An 83-year-old man with diarrhea was referred to our hospital in July 2019. Colonoscopy revealed a 4.0cm rectal carcinoma. A robot-assisted laparoscopic Hartmann operation was performed in October 2019. The patient was discharged 13 days after the procedure. Positron emission tomography-computed tomography conducted a year after surgery revealed a remnant rectum with lymph node metastasis. Colonoscopy showed a rectal carcinoma on the anal side from the remnant rectum. A Hartmann operation was performed in November 2020. Histopathology examination showed local recurrence. His postoperative course was unremarkable, and he was discharged seven days after the procedure. Intramural metastasis is rare in rectal carcinoma cases, and the frequency and specifics of its pathophysiology remain unknown. We report a case of intramural metastasis on the anal side of the remnant rectum, after a previous operation for rectal carcinoma with intravenous tumor thrombus.