A 38-year-old female patient with gastric cancer, of which histological type was a poorly differenciated adenocarcinoma and a clinical finding was T3N1MO (Stage IIIA), underwent total gastrectomy with D2 lymphadenectomy as the surgical treatment. However, CY1 was detected during the operation and the final finding was T3N1MOHOPOCY1 (Stage IV). Because this surgical treatment ended in curative C, we administered 80 mg/m2/day of TS-1 for four weeks followed by two weeks rest per one course for CY1 after the surgical treatment. After two courses of TS-1 monotherapy, extensive carcinomatous ascites appeared and blood concentration level of CA19-9 increased. We next treated this patient with TS-1+paclitaxel as a second line chemotherapy, because both of them have been reported to migrate to peritoneal very well and to be effective for peritoneal dissemination. The regimen of this combined therapy consisted of four weeks administration of TS-1 (80 mg/m2/day) followed by two weeks rest and injections of paclitaxel (50 mg/m2) at day 1 and 8 for 21 days as one course. When this patient underwent TS-1+paclitaxel combined treatment, the amount of carcinomatous ascites and blood concentration level of CA19-9 were gradually reduced and the former completely disappeared, and the latter fell to a normal range after five courses. Through all treatment courses, a performance status of this patient was kept 0 without a severe adverse event under ambulatory treatment. After 29 courses, the blood concentration level of CA19-9 rose again and local recurrence was detected at the lesion of esophagoenterostomy, though carcinomatous ascites had been kept in complete remission. We treated surgically for this local recurrence because of CY0 at the operation. At the present, 3 years and 8 months have passed since the first treatment started. This patient is still alive without cancer in ambulatory.