Automatic fire extinguisher

The object of the present invention is to achieve quick and effective fire extinguishment by sufficient diffusion of fire extinguishing agents while speeding up response during the fires. The solution of the present invention is that the automatic fire extinguisher 10 is provided with a breaking means 14 for applying impacts to tear up a fire extinguishing agent container 12 housing the fire extinguishing agent 13. The breaking means 14 is provided with a fixed plate 19 fixed at the central part on the side of the fire extinguishing agent container 12 on the bottom wall 11a of a holder 11, a guide member 22 suspended on the side of the fire extinguishing agent container 12 of the fixed plate 19, a movable plate 21 arranged on an outer circumferential surface on the side 22a of the base end part of the guide member 22, an elastic body 20 interposed between the fixed plate 19 and the movable plate 21 and the breaking member 23 fastened on the outer circumferential surface of the tip part of the guide member 22 with a heat sensitive material 29.