Altered antioxidant status has been implicated in schizophrenia. Microglia are major sources of free radicals such as superoxide in the brain, and play crucial roles in various brain diseases. Recent postmortem and imaging studies have indicated microglial activation in the brain of schizophrenia patients. Animal models that express some phenotypes of schizophrenia have revealed the underlying microglial pathology. In addition, minocycline, an antibiotic and the best known inhibitor of microglial activation, has therapeutic efficacy in schizophrenia. We have recently revealed that various antipsychotics directly affect microglia via proinflammatory reactions such as oxidative stress, by in vitro studies using rodent microglial cells. Based on these findings, we have suggested that microglia are crucial players in the brain in schizophrenia, and modulating microglia may be a novel therapeutic target. In this review paper, we introduce our hypothesis based on the above evidence. The technique of in vivo molecular redox imaging is expected to be a powerful tool to clarify this hypothesis.