The control unit, when a first condition in which a minimum value of a suppliable time that is a time it takes for an amount of liquid contained in each supply-side sub tank to reach an amount corresponding to a switching preparation time necessary for switching between the refill-side sub tank and the supply-side sub tank is less than or equal to a maximum value of a full refill refilling time that is a period from when refill processing for performing refilling of the liquid from the main tank is started in each of the plurality of refill-side sub tanks until a state is achieved in which the refill-side sub tank is fully re-filled with liquid and can supply the liquid is satisfied, the refill processing is performed on the plurality of refill-side sub tanks.