A sensor terminal which processes a sensor signal output from at least one sensor and transmits the sensor signal being processed to a center device through a network control unit and a communication line, includes a communication interface unit capable of being connected to the network control unit, a sensor input interface unit being connected to the sensor and inputting the sensor signal, and a control unit generating sensor data from the sensor signal input through the sensor input interface unit and transmitting sensor data corresponding to a request signal of the center device which is input through the communication interface unit from the network control unit or active sensor data to the center device through the network control unit from the communication interface unit.