A liquid ejection device includes a transport unit, a medium support unit, a liquid ejection head and a negative pressure generating unit. The medium support unit is arranged on a downstream side of the transport unit, and has a medium support surface on which the ejection medium is supported by suction using negative pressure. The medium support unit includes a plurality of first and second recesses arranged on the medium support surface and aligned in a width direction orthogonal to a transport direction. The first recesses are in communication with the negative pressure generating unit. The second recesses are configured and arranged to accept the liquid ejected from the liquid ejection head. Each of the second recesses includes a communication unit communicating with one of the first recesses and a vent hole configured and arranged to allow ventilation without being in communication with the negative pressure generating unit.