Inflammatory bowel disease, which is associated with symptoms such as abdominal pain and abnormal bowel movements, is an intractable disease that causes severe abnormalities in gastrointestinal motility. Rhythmic contraction of the gastrointestinal tract is regulated by the myenteric plexus (interstitial cells of Cajal: ICC) distributed between the longitudinal muscle layer and circular muscle layer. It has been considered that the rhythmic contraction is controlled by Ca²⁺ signals via Ca²⁺ channels and transporters in ICCs and smooth muscle cells. The Na⁺/Ca²⁺ exchanger type-1 (NCX1) is abundantly expressed in smooth muscle cells, which is thought to be involved in contraction and relaxation of smooth muscle cells. However, the roles of NCX1 in the rhythmic contraction of the gastrointestinal tract is still unclear. In this study, we investigated the functional role of NCX1 in rhythmic contraction of the ileum, using several types of NCX1 genetically modified mice and selective NCX1 inhibitors. As the results, it is suggested that NCX1 in ileal ICC and longitudinal muscle smooth muscle cells regulates their respective intracellular Ca²⁺ dynamics, and is complexity involved in the frequency and amplitude of rhythmic contractions.