Provided is a liquid ejection device including a liquid container tray that can suppress change in orientation and position of a liquid container on a support surface due to the difference in size of the liquid container.The liquid ejection device includes: a casing including a guide wall: a liquid container tray configured to support a liquid container: and a recording head that ejects liquid supplied from the liquid container that is supported by the liquid container tray to a medium. The liquid container tray is configured to be inserted to or removed from a casing along the guide wall, and includes a support surface that supports the liquid container and a movable wall configured to move in at least one direction on the support surface.