This emitter has an emitter body having at least a concavity and a through-hole, and also has a flexible film that is joined to one or more surfaces of the emitter body, and blocks at least part of the opening of the through-hole and the concavity. The emitter also has a flow reduction part for reducing the flow of an irrigation liquid according to the pressure of the irrigation liquid inside the tube. The flow reduction part includes the concavity, a diaphragm which constitutes part of the film, and a valve seat to which it is possible to tightly adhere the diaphragm. The diaphragm includes a ring-shaped thin section positioned so as to surround the diaphragm region to be tightly adhered to the valve seat. The thin section is formed so as to both recess from the tube interior and also project toward the concavity.
