An ultrafine bubble generating apparatus configured to generate ultrafine bubbles in liquid, the ultrafine bubble generating apparatus comprising: a liquid discharger configured to discharge liquid; a gas incorporating device configured to pressurize gas and incorporate the gas into liquid discharged from the liquid discharger; and an ultrafine bubble generator configured to generate ultrafine bubbles in liquid by allowing liquid having gas incorporated therein to pass through an inside of the ultrafine bubble generator, wherein ultrafine bubbles generated by the ultrafine bubble generator are nanobubbles with a diameter of less than 1 μm, wherein a discharge port of the liquid discharger is connected with a pressurized water transport line, wherein the gas incorporating device includes a pressurized gas generation source and a gas incorporating device body and is configured to, between the liquid discharger and the ultrafine bubble generator, pressurize gas and incorporate the gas into liquid being in a pressurized state and flowing toward the ultrafine bubble generator, wherein a gas transport line extends from the pressurized gas generation source, wherein the gas incorporating body includes a liquid passing portion through which water discharged from the liquid discharger passes and a gas passing portion through which pressurized gas from the pressurized gas generation source passes, wherein the liquid passing portion is divided into a first uniform diameter section connected with the pressurized water transport line, a diameter increasing section which is continuous with a downstream-side end of the first uniform diameter section, and a second uniform diameter section which is continuous with a downstream-side end of the diameter increasing section, wherein an inner diameter of the second uniform diameter section is smaller than a bore diameter of the pressurized water transport line, wherein the gas passing portion is divided into a connection section joined to the gas transport line, a narrowed section which is continuous with an end part of the connection section, and an injection section which is continuous with an end part of the narrowed section, wherein the gas passing portion is configured such that the gas having entered the narrowed section is introduced into the second uniform diameter section through the injection section after the flow rate thereof is reduced in the narrowed section, and wherein the ultrafine bubble generator is a nozzle and is configured to eject nanobubble-containing liquid from a tip part of the nozzle. a liquid discharger configured to discharge liquid; a gas incorporating device configured to pressurize gas and incorporate the gas into liquid discharged from the liquid discharger; and an ultrafine bubble generator configured to generate ultrafine bubbles in liquid by allowing liquid having gas incorporated therein to pass through an inside of the ultrafine bubble generator, wherein ultrafine bubbles generated by the ultrafine bubble generator are nanobubbles with a diameter of less than 1 μm, wherein a discharge port of the liquid discharger is connected with a pressurized water transport line, wherein the gas incorporating device includes a pressurized gas generation source and a gas incorporating device body and is configured to, between the liquid discharger and the ultrafine bubble generator, pressurize gas and incorporate the gas into liquid being in a pressurized state and flowing toward the ultrafine bubble generator, wherein a gas transport line extends from the pressurized gas generation source, wherein the gas incorporating body includes a liquid passing portion through which water discharged from the liquid discharger passes and a gas passing portion through which pressurized gas from the pressurized gas generation source passes, wherein the liquid passing portion is divided into a first uniform diameter section connected with the pressurized water transport line, a diameter increasing section which is continuous with a downstream-side end of the first uniform diameter section, and a second uniform diameter section which is continuous with a downstream-side end of the diameter increasing section, wherein an inner diameter of the second uniform diameter section is smaller than a bore diameter of the pressurized water transport line, wherein the gas passing portion is divided into a connection section joined to the gas transport line, a narrowed section which is continuous with an end part of the connection section, and an injection section which is continuous with an end part of the narrowed section, wherein the gas passing portion is configured such that the gas having entered the narrowed section is introduced into the second uniform diameter section through the injection section after the flow rate thereof is reduced in the narrowed section, and wherein the ultrafine bubble generator is a nozzle and is configured to eject nanobubble-containing liquid from a tip part of the nozzle.