To distribute more accurate monitoring information to monitoring terminal equipment in a monitoring system for distributing monitoring information to the monitoring terminal equipment away from a monitoring target place.

In the monitoring system including a monitoring device 100 and monitoring terminal equipment 140 for distributing sensor information or monitoring information obtained by the monitoring sensor 104 or the monitoring camera 101 of the monitoring device through a communication network 110 to the monitoring terminal equipment, the monitoring device is provided with a video saving means for saving monitoring video for fixed time while updating it and for relating the saved monitoring video with the reaction time point of the monitoring sensor, and when the monitoring sensor reacts, the sensor information is transmitted to the monitoring terminal equipment. When the transmission of the monitoring video is requested from the monitoring terminal equipment side in response to the transmission, the monitoring video for the fixed time before and after the reaction time point of the monitoring sensor is transmitted to the monitoring terminal equipment.