A pressurized gas injection device suitable for injecting a medicine in form of a pressurized gas, comprising: a discharging unit having a discharging opening and a vent hole; a gas storage unit movably disposed in the discharging unit, wherein a gas channel is formed in the gas storage unit and a chamber connected to the gas channel, wherein the gas storage unit comprises a hollow body and a rod, the rod being inserted into the body in a position-adjustable manner such that a volume of the chamber is adjustable, and the chamber, which is configured to store the pressurized gas, is formed between the body and the rod; and two seal rings (O1, O2) disposed on an inner wall of the discharging unit, wherein the seal rings (O1, O2) abut the gas storage unit; wherein the pressurized gas injection device is configured such that: when the gas storage unit is located at a first position relative to the discharging unit, a pressurized gas is allowed to enter the chamber through the vent hole and the gas channel in that order, and the gas channel is located between the seal rings (O1, O2); and when the gas storage unit moves from the first position to a second position relative to the discharging unit, the gas channel moves to be located between the discharging opening and one of the seal rings (O1, O2) that is closest to the discharging opening so that the pressurized gas in the chamber is released from the pressurized gas injection device so as to penetrate the skin of a user through the gas channel and the discharging opening in that order, wherein the pressure of the pressurized gas is greater than or equal to 5 MPa. a discharging unit having a discharging opening and a vent hole; a gas storage unit movably disposed in the discharging unit, wherein a gas channel is formed in the gas storage unit and a chamber connected to the gas channel, wherein the gas storage unit comprises a hollow body and a rod, the rod being inserted into the body in a position-adjustable manner such that a volume of the chamber is adjustable, and the chamber, which is configured to store the pressurized gas, is formed between the body and the rod; and two seal rings (O1, O2) disposed on an inner wall of the discharging unit, wherein the seal rings (O1, O2) abut the gas storage unit; wherein the pressurized gas injection device is configured such that: when the gas storage unit is located at a first position relative to the discharging unit, a pressurized gas is allowed to enter the chamber through the vent hole and the gas channel in that order, and the gas channel is located between the seal rings (O1, O2); and when the gas storage unit moves from the first position to a second position relative to the discharging unit, the gas channel moves to be located between the discharging opening and one of the seal rings (O1, O2) that is closest to the discharging opening so that the pressurized gas in the chamber is released from the pressurized gas injection device so as to penetrate the skin of a user through the gas channel and the discharging opening in that order, wherein the pressure of the pressurized gas is greater than or equal to 5 MPa. when the gas storage unit is located at a first position relative to the discharging unit, a pressurized gas is allowed to enter the chamber through the vent hole and the gas channel in that order, and the gas channel is located between the seal rings (O1, O2); and when the gas storage unit moves from the first position to a second position relative to the discharging unit, the gas channel moves to be located between the discharging opening and one of the seal rings (O1, O2) that is closest to the discharging opening so that the pressurized gas in the chamber is released from the pressurized gas injection device so as to penetrate the skin of a user through the gas channel and the discharging opening in that order, wherein the pressure of the pressurized gas is greater than or equal to 5 MPa.