The moisturizing apparatus includes: a liquid retainer arranged at a position facing a nozzle surface of a liquid ejection head, the nozzle surface being inclined relative to a horizontal plane, the liquid retainer being divided, along a direction of an inclination, into an uppermost liquid chamber, a lowermost liquid chamber and a middle liquid chamber arranged between the uppermost and lowermost liquid chambers, to store a moisturizer; a supply device which supplies the moisturizer to a liquid supply port provided in the middle liquid chamber, the supply device passing the moisturizer from the middle liquid chamber into the lowermost liquid chamber; and a discharge device which discharges the moisturizer from a waste liquid port provided in the middle liquid chamber, wherein the uppermost liquid chamber and a gas space in the lowermost liquid chamber are linked through.