A lightweight fire extinguisher is disclosed. In one embodiment, the fire extinguisher, which is portable, includes a press-source fluid container capable of retaining compressed air; extinguishant containers capable of retaining extinguishant; a pressure-source fluid tube connected to the pressure-source fluid container and the extinguishant containers, for leading the compressed air retained in the pressure-source container to the extinguishant containers; a pressure reducing valve intervening in the pressure-source fluid tube, for reducing pressure of the compressed air flowing down the pressure-source fluid tube; discharge device capable of discharging the extinguishant retained in the extinguishant containers; and an extinguishant tube connected to the extinguishant containers and the discharge device, for leading the extinguishant retained in the extinguishant containers to the discharge device.