Extinguishant composition

An extinguishant composition comprising 20 to 50% by mass of a fuel and 80 to 50% by mass of a chlorate, and further 6 to 1000 parts by mass of a potassium salt in relation to a total of 100 parts by mass of the fuel and the chlorate, and the extinguishant composition having a thermal decomposition starting temperature in the range of over 90° C. to 260° C., wherein

• the potassium salt is at least one selected from the group consisting of potassium acetate, potassium propionate, monopotassium citrate, dipotassium citrate, tripotassium citrate, potassium trihydrogen ethylenediaminetetraacetate, dipotassium dihydrogen ethylenediaminetetraacetate, tripotassium hydrogen ethylenediaminetetraacetate, tetrapotassium ethylenediaminetetraacetate, potassium hydrogen phthalate, dipotassium phthalate, potassium hydrogen oxalate, dipotassium oxalate, and potassium bicarbonate,
• the fuel is at least one selected from the group consisting of dicyandiamide, nitroguanidine, guanidine nitrate, urea, melamine, melamine cyanurate, avicel, guar gum, sodium carboxymethylcellulose, potassium carboxymethylcellulose, ammonium carboxymethylcellulose, nitrocellulose, aluminum, boron, magnesium, magnalium, zirconium, titanium, titanium hydride, tungsten, and silicon, and
• the extinguishant composition is configured to be ignited automatically by a heat due to a fire or ignited by a device having an initiator or a detonator.