Abstract: There is provided a simple fire extinguishing apparatus comprising a fire sensor 2 and a fire extinguishing water spraying head 3 positioned at required positions, a water tank 1 serving as a water supply source, a level switch 13 and a resupply port 10 which is not in contact with the water surface, installed in the water tank 1, a driving pump 7, a main pipe 5 allowing the suction and delivery sides of the driving pump 7 respectively to communicate with the water tank 1 and the fire extinguishing water spraying head 3, a control valve 8 installed in the main pipe 5 and adapted to be actuated by the fire sensor 2 and the level switch 13, a resupply pipe 4 branching from a tap water pipe 11 and extending to communicate with the resupply port 10, and a control valve 9 installed in the resupply pipe 4 and adapted to be actuated by the fire sensor 2 and the level switch 13, the arrangement being such that when a fire breaks out, water is fed from the water tank 1 through the main pipe 5 to the fire extinguishing