A liquid circulation unit adapted to be provided in a liquid circulation apparatus to circulate a liquid, including, a first liquid storage unit to store the liquid, a sensor to detect a fluid level of the liquid stored in the first liquid storage unit, a liquid sending pump to send the liquid to an outside from the first liquid storage unit based on a detection result of the sensor, a pipe arrangement for deaeration to remove a dissolved gas in the liquid sent from the liquid sending pump, a filter to remove an impurity in the liquid sent from the liquid sending pump, a diaphragm valve which opens when the liquid is sent to the outside from the first liquid storage unit, and a cock valve which opens when the liquid is sent to the first liquid storage unit from the outside, wherein the liquid circulation unit is adapted to be provided so as to be detachable to or from the liquid circulation apparatus.