The present invention relates to a needleless injection device comprising a cannula (5) that can be inserted into the housing (3) which can be filled with the agent to be injected to a predetermined. The cannula is movable within the cannula housing, it is used to push the active substance from the discharge port that is included with the cannula housing (11). The injection device of the present invention, furthermore, the propellant cartridge may be inserted into and housing (3) comprises a housing with a propellant (19) (7), an ignition device for igniting the propellant (23) equipped with. Moreover, the injection device of the present invention comprises a cannula (5) into or cartridge housing the housing of the injection device (1) Promotion surface member is movable within a portion of the housing (3a) of the (15). Promotion surface body, after the propellant has been ignited by the gas pressure generated by it, can be moved from the initial position to the end position, the outer circumferential surface of the propulsion surface body, during all movement, respectively It is sealed to the inner circumferential surface of the housing. Promotion surface body (15) pushes the piston (9) movable within the cannula housing.