A drip irrigation emitter for controlling an amount of irrigation liquid ejected through an ejection port of a flow pipe through which the irrigation liquid flows, the ejection port extending through a pipe wall of the flow pipe, wherein the drip irrigation emitter is disposed on inner peripheral surface of tube main body at a position corresponding to ejection port for irrigation liquid, so as to cover ejection port, the drip irrigation emitter comprising: a flow channel that allows the irrigation liquid in the flow pipe to flow from an inside of the flow pipe to the ejection port when the drip irrigation emitter is disposed at a position corresponding to the ejection port in an inner peripheral surface of the flow pipe; an inflow part for introducing the irrigation liquid in the flow pipe into the flow channel; a pressure reduction channel part disposed on a downstream side relative to the inflow part in the flow channel, the pressure reduction channel part being configured to define a pressure reduction channel together with the inner peripheral surface of the flow pipe, the pressure reduction channel being configured to allow the irrigation liquid entered from the inflow part to flow therethrough toward the ejection port while reducing a pressure of the irrigation liquid; a diaphragm part disposed on a downstream side relative to the inflow part in the flow channel such that the diaphragm part is partially exposed in the flow pipe, that the diaphragm is exposed to the liquid pressure of the irrigation liquid in the flow pipe, and that the diaphragm is deformed toward the inner peripheral surface of the flow pipe, a first plane to be connected to the inner peripheral surface of the flow pipe; and a second plane to be located on a central axis side of the flow pipe relative to the first plane, wherein the inflow part is disposed at the second plane, the diaphragm part limits a height of the flow channel such that the height of the flow channel decreases as the liquid pressure increases by being deformed toward the inner peripheral surface of the flow pipe in accordance with the liquid pressure, and the inflow part, the pressure reduction channel part and the diaphragm part are integrally formed with a resin material, the diaphragm part includes a thin central wall part having a curved shape protruding in a direction away from the inner peripheral surface of the flow pipe defining the pressure reduction channel, and a thin peripheral wall part connected to an outer peripheral edge of the central wall part in such a manner as to surround the central wall part, the peripheral wall part having a shape gradually expanding in the direction away from the inner peripheral surface of the flow pipe; and, the drip irrigation emitter further comprises an opening part that opens to the second plane and connects the flow channel and an outside together; and is characterized in that the diaphragm part is so disposed at the opening part as to be partially exposed to the outside. a flow channel that allows the irrigation liquid in the flow pipe to flow from an inside of the flow pipe to the ejection port when the drip irrigation emitter is disposed at a position corresponding to the ejection port in an inner peripheral surface of the flow pipe; an inflow part for introducing the irrigation liquid in the flow pipe into the flow channel; a pressure reduction channel part disposed on a downstream side relative to the inflow part in the flow channel, the pressure reduction channel part being configured to define a pressure reduction channel together with the inner peripheral surface of the flow pipe, the pressure reduction channel being configured to allow the irrigation liquid entered from the inflow part to flow therethrough toward the ejection port while reducing a pressure of the irrigation liquid; a diaphragm part disposed on a downstream side relative to the inflow part in the flow channel such that the diaphragm part is partially exposed in the flow pipe, that the diaphragm is exposed to the liquid pressure of the irrigation liquid in the flow pipe, and that the diaphragm is deformed toward the inner peripheral surface of the flow pipe, a first plane to be connected to the inner peripheral surface of the flow pipe; and a second plane to be located on a central axis side of the flow pipe relative to the first plane, wherein the inflow part is disposed at the second plane, the diaphragm part limits a height of the flow channel such that the height of the flow channel decreases as the liquid pressure increases by being deformed toward the inner peripheral surface of the flow pipe in accordance with the liquid pressure, and the inflow part, the pressure reduction channel part and the diaphragm part are integrally formed with a resin material, the diaphragm part includes a thin central wall part having a curved shape protruding in a direction away from the inner peripheral surface of the flow pipe defining the pressure reduction channel, and a thin peripheral wall part connected to an outer peripheral edge of the central wall part in such a manner as to surround the central wall part, the peripheral wall part having a shape gradually expanding in the direction away from the inner peripheral surface of the flow pipe; and, the drip irrigation emitter further comprises an opening part that opens to the second plane and connects the flow channel and an outside together; and is characterized in that the diaphragm part is so disposed at the opening part as to be partially exposed to the outside.