A syringe used to inject an injection objective substance to an injection target area, comprising: a syringe main body including a through-bore extending along the axial direction; a first piston part arranged in such a way as to be capable of sliding in said through-bore; a syringe unit disposed on the front end of said syringe main body and including a container chamber capable of containing said injection objective substance, a plunger that pressurizes said injection objective substance in said container chamber with sliding motion of said first piston part, and a nozzle part that has a fluid channel through which said injection objective substance pressurized by said plunger in said container chamber flows and ejects said injection objective substance from an ejection port provided at the end of said fluid channel; an igniter that causes powder to burn and applies ejection energy for ejecting said injection objective substance from said nozzle part to said first piston part by the combustion of powder in said igniter; and a sealing member that separates the space in said syringe main body into a first space in which said igniter is disposed and a second space in which said first piston part is disposed and confines combustion products produced by said igniter in said first space, wherein said sealing member is made of an elastic material, wherein said first piston part has a plunger side end portion that is in contact with said plunger and a specific end portion including a specific end face that receives said ejection energy, said sealing member has a fixed end portion fixed to an inner wall that defines the space in said syringe main body and a contact portion that is in contact with said specific end face of said specific end portion when the powder burns in said igniter, wherein the syringe is configured such that, when in use and in a state before the combustion of powder in said igniter, said contact portion is located at an initial position on an igniter side of said fixed end portion, and when in use and with the combustion of powder in said igniter, said contact portion shifts to an ejection position on a syringe unit side of said fixed end portion with sliding motion of said first piston part while being in contact with said specific end face. a syringe main body including a through-bore extending along the axial direction; a first piston part arranged in such a way as to be capable of sliding in said through-bore; a syringe unit disposed on the front end of said syringe main body and including a container chamber capable of containing said injection objective substance, a plunger that pressurizes said injection objective substance in said container chamber with sliding motion of said first piston part, and a nozzle part that has a fluid channel through which said injection objective substance pressurized by said plunger in said container chamber flows and ejects said injection objective substance from an ejection port provided at the end of said fluid channel; an igniter that causes powder to burn and applies ejection energy for ejecting said injection objective substance from said nozzle part to said first piston part by the combustion of powder in said igniter; and a sealing member that separates the space in said syringe main body into a first space in which said igniter is disposed and a second space in which said first piston part is disposed and confines combustion products produced by said igniter in said first space, wherein said sealing member is made of an elastic material, wherein said first piston part has a plunger side end portion that is in contact with said plunger and a specific end portion including a specific end face that receives said ejection energy, said sealing member has a fixed end portion fixed to an inner wall that defines the space in said syringe main body and a contact portion that is in contact with said specific end face of said specific end portion when the powder burns in said igniter, wherein the syringe is configured such that, when in use and in a state before the combustion of powder in said igniter, said contact portion is located at an initial position on an igniter side of said fixed end portion, and when in use and with the combustion of powder in said igniter, said contact portion shifts to an ejection position on a syringe unit side of said fixed end portion with sliding motion of said first piston part while being in contact with said specific end face.