PROBLEM TO BE SOLVED: To provide a needle-free injector that can selectively guide an immune response, and provide a method for introducing DNA including an area of encoding an antigen that selectively creates an antibody in a living body of a mammal by using the needle-free injector.SOLUTION: A needle-free injector 1 is provided for injecting DNA solution into an injection target area without passing through a needle. The needle-free injector includes: a filling chamber 32 for receiving the DNA solution: a predetermined igniter 71； and a nozzle part 31 having an ejection port 31a where the DNA solution pressurized by burning the predetermined igniter with the igniter is made to flow and be ejected to the injection target area. The needle-free injector is configured such that a predetermined temperature of a combustion product during pressurization transits to near a normal temperature within 20 msec after the pressure applied to the DNA solution by the burning of the igniter reaches an initial peak injection force in the pressurization process for ejection of the DNA solution.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2017,JPO&INPIT【課題】免疫応答を選択的に誘導できる無針注射器、及び、無針注射器を用いて哺乳動物の生体内に抗体を選択的に作成させる抗原をコードする領域を含むＤＮＡを導入する方法を提供する。【解決手段】注射針を介することなく、ＤＮＡ溶液を注射対象領域に注射する無針注射器１であって、ＤＮＡ溶液を収容する充填室３２と、所定の点火器７１と、点火器での所定の点火薬の燃焼により加圧されたＤＮＡ溶液が流れ、注射対象領域に対して射出される射出口３１ａを有するノズル部３１と、を備え、ＤＮＡ溶液の射出のための加圧過程において、該加圧時の所定の燃焼生成物の温度が、点火薬の燃焼によりＤＮＡ溶液に掛かる圧力が最初のピーク射出力を迎えてから２０ｍｓｅｃ以内に、常温近傍まで推移する、無針注射器。【選択図】図１
