ALARM SYSTEM

PROBLEM TO BE SOLVED: To provide a fire alarm system in which misdetection of fire can be prevented, and in which even if a warning is issued as misdetection notification, the wrong notification can be surely prevented thereafter, and the system can be used continuingly. SOLUTION: The alarm system is provided with a light-emitting part 11 for emitting detection light, a light-receiving part 12 for receiving a scattered light of the detection light, and a light-blocking part 13 for preventing the detection light emitted from the light-emitting part 11 from directly reaching the light-receiving part 12 in a dark chamber 10 that can let in ambient air inside, while blocking the external light. The alarming system is also provided with a foreign object removing means for removing a foreign object X that adheres to at least one among the light-emitting part 11, the light-receiving part 12, and the light-blocking part 13, from these members. COPYRIGHT: (C)2009,JPO&INPIT