The serendipitous discovery of drugs with antipsychotic action has provided a clue to understanding the pathogenesis of psychotic disorders and to develop so called ‘antipsychotics’ drugs. From the ‘dopamine hypothesis’ to current molecular psychiatry findings, researchers have endeavored to improve the understanding of the mechanism of action of antipsychotic drugs. Signaling molecules were examined as novel intracellular targets of antipsychotic action. The findings regarding the effects of antipsychotics on inflammation, metabolism, and cellular fate have helped conceptualize the biological action of antipsychotics. This review summarizes the current knowledge of the molecular psychiatry findings regarding the action mechanisms of antipsychotics. The accumulation of research findings will lead to a better understanding of the pathogenesis of schizophrenia and its treatment mechanism.