Inclusion Criteria:

- Histologically confirmed adenocarcinoma of the stomach

- Unresectable metastatic disease or recurred AGC

- Age ≥ 20 years old

- Eastern Cooperative Oncology Group performance status 0-2

- Estimated life expectancy > 12weeks

- Patients with pre-treatment(radiotherapy, chemotherapy) is not carried out. (However,
adjuvant chemotherapy using one kind of medication is allowed. It must passed more
than 6 months since end of the treatment.) Conventional radiation therapy should be
performed before more than 2 weeks. And it is not allowed radiation therapy on
primary tumor, measurable lesions, and abdominal

- According to RECIST ver.1.1, using imaging techniques (CT or MRI), measurement
possible disease or not measurable, but assessable disease

- Screening laboratory values within the following limits : Hemoglobin ≥ 9 g/dL,
Absolute neutrophil count ≥ 1.5 x 10³/L, Platelet count ≥ 75 x 10³/L, Serum
creatinine ≤ 1.5 x UNL, Creatinine clearance ≥ 50 mL/min, AST/ALT ≤ 5.0 x UNL

- The patient or protector have to sign a consent form. And he should be able to
understand the right to withdraw consent without disadvantage.

Exclusion Criteria:

- Prior chemotherapy (however, previous (neo-)adjuvant chemotherapy allowed if finished
at least 6month ago except S-1, Paclitaxel, Docetaxel, Oxaliplatin . Allowed 5-FU,
Cisplatin if finished 6month ago)

- Patients with oral intake is impossible or with malabsorption syndrome

- Patients with medically uncontrolled severe complications or infection

- Patients who have central nervous system disorders, mental disorders, or evidence of
CNS metastases

- Patient with diagnosed active overlapping cancer within the past 5years except
adequately treated carcinoma insitu of the cervix, basal or squamous cell carcinoma
of skin

- The possibility(will) of pregnancy , or pregnant and lactating women

- Patients with clinically significant heart disease

- Progression of gastric lesions is not possible to evaluate

- During clinical trials, patient receiving of systemic chemotherapy or other clinical
trials drugs or radiotherapy (However, it is possible that palliative radiotherapy
treatment for pain relief on primary lesion after more than 2 weeks)

- Peripheral neuropathy of Grade 2 or greater.

- Patients who taking drugs to change of pharmacological activity of S-1
medicine(Warfarin, phenytoin, allopurinol etc.). Except regular treatment of
corticosteroids(or equivalent drugs). However, it is allowed the purposes for
pre-treatment of study drugs and the control of nausea and vomiting. (However, it is
allowed the treatment for acute allergic reactions, or the treatment with low doses
(methylprednisolone 20mg or less, or the equivalent drug) from about 6 months)

- Other cases

- Concurrent disease or condition that would make the subject inappropriate for
study participation or any serious medical disorder that would interfere with
the subject's safety.

- Psychological condition or dementia that would not permit the subject to
complete the study or sign informed consent

- Patients with dropout sure in clinical trials or cannot be regular follow-up
following reasons. For example, psychological, social, family, geographic
reasons or a difficult condition of compliance with clinical trial and proper
follow up.

- Poorly controlled chronic liver disease or diabetes mellitus

- Else, in the investigator's opinion, should exclude the patient from the study.