A syringe for injecting an injection objective substance into an injection target area of a living body without using any injection needle, the syringe comprising: an ignition device which includes an ignition charge containing a fuel component and an oxidizing agent component; a combustion chamber into which a combustion product produced by a reaction of the fuel component and the oxidizing agent component during combustion of the ignition charge is allowed to flow and which accommodates a gas generating agent that is combustible by the combustion product to generate a predetermined gas; an enclosing unit which encloses the injection objective substance; a pressurizing unit which is constructed to pressurize the injection objective substance enclosed in the enclosing unit by means of a pressure in the combustion chamber; and a flow passage unit which defines a flow passage so that the injection objective substance, which is pressurized by the pressurizing unit, is allowed to inject to the injection target area of the living body, wherein: the fuel component and the oxidizing agent component contained in the ignition charge are determined so that any component, which behaves as a gas, is excluded from the combustion product when the combustion product is at ordinary temperature in the case where the fuel component and the oxidizing agent component are mixed at a stoichiometric ratio and combusted; and a cooling member is arranged in the combustion chamber so that the cooling member can be brought in contact with the combustion product produced by the combustion of the ignition charge to cool the combustion product, characterized in that the cooling member is arranged along a side wall of the combustion chamber positioned in a direction in which the combustion product flow into the combustion chamber. an ignition device which includes an ignition charge containing a fuel component and an oxidizing agent component; a combustion chamber into which a combustion product produced by a reaction of the fuel component and the oxidizing agent component during combustion of the ignition charge is allowed to flow and which accommodates a gas generating agent that is combustible by the combustion product to generate a predetermined gas; an enclosing unit which encloses the injection objective substance; a pressurizing unit which is constructed to pressurize the injection objective substance enclosed in the enclosing unit by means of a pressure in the combustion chamber; and a flow passage unit which defines a flow passage so that the injection objective substance, which is pressurized by the pressurizing unit, is allowed to inject to the injection target area of the living body, wherein: the fuel component and the oxidizing agent component contained in the ignition charge are determined so that any component, which behaves as a gas, is excluded from the combustion product when the combustion product is at ordinary temperature in the case where the fuel component and the oxidizing agent component are mixed at a stoichiometric ratio and combusted; and a cooling member is arranged in the combustion chamber so that the cooling member can be brought in contact with the combustion product produced by the combustion of the ignition charge to cool the combustion product, characterized in that the cooling member is arranged along a side wall of the combustion chamber positioned in a direction in which the combustion product flow into the combustion chamber. the fuel component and the oxidizing agent component contained in the ignition charge are determined so that any component, which behaves as a gas, is excluded from the combustion product when the combustion product is at ordinary temperature in the case where the fuel component and the oxidizing agent component are mixed at a stoichiometric ratio and combusted; and a cooling member is arranged in the combustion chamber so that the cooling member can be brought in contact with the combustion product produced by the combustion of the ignition charge to cool the combustion product, characterized in that the cooling member is arranged along a side wall of the combustion chamber positioned in a direction in which the combustion product flow into the combustion chamber.