1. A monitoring system comprising: an acquiring unit which acquires first sensor data from a first sensor and second sensor data from a second sensor; a state-data description unit which, based on the first sensor data and second sensor data acquired by said acquiring unit, describes state data concerning response states of the first and second sensors, wherein the state data includes a response symbol classified in accordance with the response state of the first sensor, a duration of the response state of the first sensor, and a characteristic value concerning the response state of the second sensor in the response state of the first sensor; a determining unit which, by comparing the state data described by said state-data description unit with a determination table, determines whether or not an event is to be reported; a creating unit which only receives image data from a camera when said determining unit determines that the event is to be reported, said creating unit creates display data based on the image data; and a display unit which displays a picture based on the display data created by said creating unit.