The pathophysiology of mental disorders remains unknown. This causes many gaps in pathophysiology, diagnosis, and treatment of mental disorders. To close these gaps, a new perspective, which is not bound by the existing diagnostic classifications or pathological hypotheses for mental disorders, is required. Recently, it has been reported that glial cells play active roles in normal brain function and circuit formation, and their disruption results in the onset of mental disorders. Here, we discuss mental disorders from the perspective of glial cell-related pathophysiology, along with our current efforts and research.