A liquid-ejection apparatus, including: a head configured to eject a liquid from a plurality of liquid-ejection openings; a main tank configured to accommodate the liquid supplied to the head; a liquid-supply pump configured to supply the liquid in the main tank to the head; a sub-tank in which are formed (a) a connection opening for connecting the sub-tank to the head and (b) an air-discharge opening for communicating the sub-tank with ambient air; a first channel extending from the liquid-supply pump to the sub-tank via the head and the connection opening; a second channel extending from the sub-tank to the liquid-supply pump; a third channel extending from the air-discharge opening of the sub-tank to the ambient air; an air-discharge valve provided in the third channel so as to be openable and closable; and a controller configured to control the air-discharge valve such that the air-discharge valve is temporarily opened in a liquid introducing operation in which the liquid is introduced from the main tank to the liquid-supply pump and an air discharging operation in which air separated from the liquid in the sub-tank by causing the liquid to be flowed through the first channel by driving of the liquid-supply pump is discharged through the third channel, and such that the air-discharge valve is closed in times other than the liquid introducing operation and the air discharging operation.