A liquid ejection device includes a liquid ejection head which ejects a first liquid, and a liquid supply unit. The liquid ejection head includes a plurality of liquid discharge holes with individual passages and a common passage for supplying the first liquid to the individual passages. The liquid supply unit includes a pressure chamber, a first supply passage communicating with the pressure chamber, and a second supply passage that makes an upstream side of a common passage communicate with the pressure chamber, a liquid drain path that makes a downstream side of the common passage communicate with the second supply passage, and a pump mechanism. The pump mechanism supplies the first liquid to the upstream side and the downstream side of the common passage through the second supply passage and the liquid drain path, and discharges the second liquid, which is filled in advance, from the liquid discharge hole.