The deaerating and dissolving apparatus or the deaerating and dissolving method includes: a pipe which is configured to feed a liquid; a flow rate control section which is provided to a middle portion of the pipe and is configured to feed the liquid at a predetermined flow rate to a downstream side; a cavity forming section which is provided to a middle portion of the pipe downstream of the flow rate control section and is configured to produce a stationary cavity which is in contact with the liquid, and a pressurization or depressurization section which pressurizes or depressurizes the inside of the cavity, wherein the liquid is deaerated when the inside of the cavity is depressurized with the pressurization or depressurization section, and a gas is dissolved into the liquid when the inside of the cavity is pressurized with the gas supplied through the pressurization or depressurization section.