This study is designed to evaluate the efficacy and safety in Social Anxiety Disorder (SAD).

Inclusion criteria:

• Diagnosis of Social Anxiety Disorder (SAD) (300.23 Social Phobia/Social Anxiety Disorder) according to DSM-IV-TR criteria.
• Must give a written informed consent. But if the patient is under 20, both the patient himself/herself and his/her proxy consenter must give written informed consent.
• Patients have a minimum score of 60 on the LSAS total score.

Exclusion criteria:

• Patients primarily diagnosed with a disorder that is categorized into Axis I excluding SAD by DSM-IV-TR (e.g. major depression, dysthymic disorder, specific phobia (simple phobia) , obsessive compulsive disorder, panic disorder) within 24weeks before week -2.
• Patients with a history or complication of schizophrenia and bipolar disorder
• Patients with a complication of body dysmorphic disorder.
• Patients with evidence of substance abuse (alcohol or drugs)
• substance dependence by DSM-IV-TR criteria within 24 weeks before week -2.
• Patients who started psychotherapy and cognitive-behavioural therapy within 24 weeks before week-2, except for supportive psychotherapy.
• Patients receiving electro-convulsive therapy (ECT) within 12 weeks before week -2.
• Patients being pregnant, lactating or are of childbearing potential and are likely to become pregnant.
• Patients with 3 or more points of HAM-D Item No. 3, or who are likely to attempt suicide.
• Patients with a history or complication of cancer or malignant tumor.
• Patients receiving MAO inhibitors (FP®) within 14 days before expected week 0 visit date.