There is provided a liquid ejection device including a head for ejecting a liquid, a liquid containing unit, a liquid filler, and a pressure adjusting unit, in which the liquid containing unit includes a sealed housing and a flexible member provided in the housing, the housing includes a first containing space communicating with the head and a second containing space partitioned from the first containing space through use of the flexible member, the first containing space contains the liquid, and the liquid filler is filled into the second containing space, the pressure adjusting unit communicates with the second containing space, and adjusts the pressure of the liquid filler filled into the second containing space so as to maintain a negative pressure with respect to the head.