In recent years, the annual number of suicide victims is over 30,000 in Japan. Most of the these suicides are considered to be caused by depressive disorders. Therefore, intervention in the early stage of depression must be performed to prevent suicide. Firstly, new antidepressant drugs such as SSRIs and SNRIs are very useful to treat depressive disorders without severe adverse effects, which might lead to a good rate of adherance to the drugs. However, the use of newer antidepressant drugs might be accompanied with some problems such as activation syndrome, serotonin syndrome, withdrawal syndrome, and suicidal-like behaviors. Secondly, it is important to predict whether the response to antidepressant drugs will shorten the treatment period. The polymorphisms of 5-HTTLPR and plasma MHPG levels might predict the response to SSRIs and SNRIs. Thirdly, we should work to achieve complete remission including social adjustment and also adjustment in the work place instead of just partial remission. SASS is one of the useful rating scales for assessing social adaptation. In addition, the continuation of maintenance treatment for a sufficient duration is necessary to prevent relapse. Taken together, early intervention with precise pharmacotherapy (ECT or rTMS in refractory cases) and psychotherapy is important to prevent suicide.