To provide a gas fire extinguisher which is free from a concern about a reduction in working efficiency of workers and is inexpensive in a cost of the installation and a cost of usage.

The gas fire extinguisher 13 is used in a plant 10 in which a production line is constructed by arranging apparatuses 11 for assembling products in the order of assembling work and extinguishes a fire occurring from the apparatus 11 by a fire-extinguishing gas sprayed from a fire extinguishing nozzle 30. A partitioning sheet (a partitioning member) 19 which is switched between an expansion mode and an accommodation mode, covers the periphery of the apparatus to fill the periphery of the apparatus with the fire-extinguishing gas sprayed from the fire-extinguishing nozzle in the expansion mode, and keeps the periphery of the apparatus open in the accommodation mode is installed on the gas fire extinguisher.