ANTI-THEFT SENSOR AND ALARM SYSTEM THEREOF

An anti-theft sensor and an alarm system thereof are provided. The alarm system includes a plurality of anti-theft sensors and an alarm device, and the plurality of anti-theft sensors are electrically connected to bolts of a vehicle frame of a vehicle to form an electrical loop/circuit, so that the plurality of anti-theft sensors must be removed when the vehicle frame is moved. In this way, when the plurality of anti-theft sensors are removed, the plurality of anti-theft sensors are triggered to send a warning signal to the alarm device, so that the alarm device sends out an alarm. Therefore, the vehicle owner can be immediately and correctly reminded that the condition of the vehicle frame of the vehicle is abnormal without false alarms.