Abstract: The invention is to prevent a nozzle located at a position immediately preceding a mixing chamber from becoming closed off with crystallized solute contained in a liquid which has become deposited and to prevent air supplied into the mixing chamber from flowing backward to a metering pump in a liquid aeration delivery apparatus for mixing the liquid with the air and delivering it. Accordingly, a liquid pressurized at a metering pump is supplied via an outlet flow passage and is injected into a mixing chamber from an orifice, but a needle is inserted into the orifice and is made to move by an electromagnetic valve used to open/close the outlet flow passage, so that the orifice is cleaned. In addition, air for mixture is supplied to the mixing chamber, but a pulse synchronous with a pulse applied to the metering pump is supplied to an air control valve provided at an air flow passage, so that supply of the air can be synchronized with the liquid supply to prevent an air backward flow.