Functional gastrointestinal disorders (FGIDs) such as functional dyspepsia (FD) and irritable bowel syndrome (IBS) are included in functional somatic syndromes (FSS), which are designated as medically unexplained physical symptoms. Pathopysiology of these diseases are characterized by multi-functional disorders of the gastrointestinal (GI) tract including psychosomatic sensation, brain-gut interaction, autonomic nervous systems, motility disorders, local inflammation, and visceral perception. However, the standard therapy for these diseases is not established, since predominant factors among them associated with respective patients are difficult to be identified in a clinical field. In this section, we are going to present the accumulating evidences for the pathophysiology and therapeutic strategy of FD and IBS.