PROBLEM TO BE SOLVED: To enable an injection object substance to be sent to a depth of a target skin structure of a living body without using an injection needle.SOLUTION: An injection syringe without an injection needle includes: an igniter a gas generating agent an encapsulation part for encapsulating an injection object substance a pressure application part for applying pressure to the injection object substance and a flow channel part for defining a flow channel. The pressure application part has a first pressure application mode in which the pressure to the injection object substance is increased to a first peak pressure to form a penetration passage in an injection target region, and then the pressure to the injection object substance is decreased to a stand-by pressure, and a second pressure application mode in which pressure is applied to the injection object substance under the stand-by pressure, the pressure to the injection object substance is increased to a second peak pressure, and the inject objection substance of a predetermined injection amount is injected. The ratio of the stand-by pressure to the first peak pressure is 50% or less.COPYRIGHT: (C)2014,JPO&INPIT【課題】注射針を介することなく注射目的物質を目的とする生体の皮膚構造体の深さに送り込むことを可能とする。【解決手段】注射針の無い注射器であって、点火薬と、ガス発生剤と、注射目的物質を封入する封入部と、注射目的物質に対して加圧する加圧部と、流路を画定する流路部と、を備える。そして、加圧部は、注射対象領域に貫通路を形成させるために注射目的物質への圧力を第一ピーク圧力まで上昇させた後、該注射目的物質への圧力を待機圧力まで下降させる第一加圧モードと、待機圧力にある注射目的物質に対して加圧を行い、該注射目的物質への圧力を第二ピーク圧力まで上昇させて、所定の注射量の注射目的物質の注射を行う第二加圧モードと、を有する。そして、第一ピーク圧力に対する待機圧力の比率が50%以下である。【選択図】図4
