Provided are: an emitter which is capable of inhibiting variation in the amount of liquid discharged from the inside of a drip irrigation tube； and a drip irrigation tube. This emitter (120), which adjusts the discharge of an irrigation liquid, is provided with: an intake part which takes in a liquid in a tube (110)； an adjustment part for the amount of the liquid discharged； a discharge part which discharges the liquid through a discharge port (112) of the tube (110)； and a flow path through which the intake part and the adjustment part communicate. The adjustment part is provided with a recess and a film. The film is fixed in a state of covering the internal space of the recess. The area covering the internal space of the recess is a diaphragm part. The recess is provided with: a through hole which communicates with the discharge part； and a plurality of slits which communicate with the through hole. An edge of the through hole forming an upper surface-side opening excluding the plurality of slits is a valve seat part. When the diaphragm part of the film is in contact with the valve seat part, a communication port to the through hole is formed by the film and each of the slits. Each of the slits forms a flow path to the through hole, and satisfies condition (1), namely when the cross sectional area required for the communication port to be formed by the film and one slit is 1, the cross sectional area of each of the communication ports to the through hole which are formed by the film and each slit is less than 1.
