A liquid supply unit supplies predetermined liquid from a liquid storage container storing the liquid to a liquid injection head for injecting the liquid. The liquid supply unit includes a pressure chamber, a first supply passage, a second supply passage, a bypass supply passage and a pressurizing mechanism. The pressure chamber is capable of storing the liquid. The first supply passage allows communication between the liquid storage container and the pressure chamber. The second supply passage allows communication between the liquid injection head and the pressure chamber. The bypass supply passage has an upstream end in a liquid supply direction connected to the first supply passage and a downstream end joining the second supply passage. The pressurizing mechanism is arranged in the bypass supply passage and pressurizes the liquid flowing in the bypass supply passage.