An ink ejection device includes: a head section ejecting a plurality of kinds of inks; and an ink supply section supplying the plurality of kinds of inks to the head section. The ink supply section includes: two outlet ports which are separated from each other in a first direction intersecting with a vertical direction and through which a first kind of ink among the plurality of kinds of inks is supplied toward the head section; and an air-trap chamber in communication with the two outlet ports. The air-trap chamber protrudes to one side of a second direction intersecting with the vertical direction and the first direction relative to the two outlet ports. A portion connecting the two outlet ports of the air-trap chamber has an arc shape in a plane containing the first direction and the second direction or a bent portion of the portion connecting the two outlet ports of the air-trap chamber has an obtuse angle in the plane.