A capping mechanism, which causes an ejection space opposing ejection openings of a liquid ejection head to take either one of a sealed state and a non-sealed state, includes an annular component which surrounds the ejection space in the sealed state and an opposing member which opposes the ejection openings with the ejection space interposed therebetween. A mechanism for supplying humidified air generates humidified air and includes a supply opening and a discharging opening. The supply opening and the discharging opening are positioned to form a humidifying passage such that the humidified air having flown along an inner circumferential surface of a first region of the annular component passes through a gap between the ejection openings and the opposing member and flows along an inner circumferential surface of a second region of the annular component, which opposes the first region.