We herein report an extremely rare operative case of an isolated extraperitoneal metastasis of colon cancer. A female patient had undergone a sigmoidectomy for ileus due to sigmoid colon cancer when she was 40 years old. Peritoneal metastasis, 5 mm in diameter, was on the sigmoid colon mesentery and she was histologically diagnosed as Stage IV. She received fluorouracil-based adjuvant chemotherapy for 24 months. Serum CEA increased gradually from 36 months after the operation, and CT scan demonstrated bilateral ovarium tumors. Bilateral oophorectomy was performed at 44 months after the operation. Serum CEA decreased temporarily, but increased again. Serum CEA increased in spite of giving UFT/LV, so we changed to mFOLFOX6 therapy. Serum CEA decreased until it reached to a normal range after 9 courses, and stopped mFOLFOX6 therapy. Four months later, serum CEA increased again and PET-CT demonstrated a 3 cm mass with calcification in pelvic, and accumulation of FDP. Serum CEA decreased until it reached to a normal range after a resection of extraperitoneal mass. A histological examination of the tumor revealed a moderately differentiated adenocarcinoma similar to colon cancer. She has been well without recurrence 77 months after the first operation.