Provided is a micro-jet drug injection device comprising: a pressure chamber having a pressure driving liquid hermetically filled therein a drug chamber having a micro nozzle defined in a wall an elastic membrane elastically expandable and restorable and to separate the pressure chamber from the drug chamber an energy-focusing unit concentrating energy on the pressure driving liquid in the pressure chamber and the storage unit supplying the drug solution therein into the drug chamber through a drug supply channel. The drug chamber has a partial inner space defined therein. The partial inner space is in fluid communication with the drug supply channel and is partially defined by the membrane. A nozzle closure is disposed inside or outside the drug chamber. The nozzle closure blocks inflow of air outside the micro-nozzle into the partial inner space after the elastic membrane has expanded and before elastic recovery of the membrane is completed.
