PURPOSE: To provide a liquid discharger and its operational control method, capable of preventing a hindrance attending on any stagnation in a transfer route and of performing the expected liquid discahrge without fail.

CONSTITUTION: A three-way valve 40 is made into a suction state, operating a pump 30 for suction, and a liquid 13 in a tank 20 is drawn in up to a common tube 50 from an inlet tube 51, while the three-way valve 40 is selected to a discharge state, operating the pump 30 for discharge, then the liquid 13 in the common tube 50 is discharged out of a discharge tube 52, whereby the pump 30 is made into suction operation in leaving the three-way valve 40 in a state of being discharged intact, and air is inhaled from the discharge tube 52. In succession, the three-way valve 40 is selected to the suction state, operating the pump 30 for discharging, and the air is also discharged, thereby returning the liquid 13 in the inlet tube 51 to the inside of the tank 20.