In order to provide a portable fire extinguisher suitable for first-aid fire extinguishing, the fire extinguisher, using as the fire-extinguishing agent inert gas, etc. not limited in the object to be extinguished and the method of use due to toxicity to human body and making easy to maintain the necessary concentration of the fire-extinguishing agent, thus securing the effective fire-extinguishing effect, has the fire-extinguishing agent storage container to which the nozzle portion to discharge the fire-extinguishing agent is connected and made portable so as to be able to discharge the fire-extinguishing agent toward the object to be extinguished, and the nitrogen gas is stored in the fire-extinguishing agent storage container and at the outlet portion of the flow route of the fire-extinguishing agent formed in the nozzle portion, a metallic porous member in installed.