A technique capable of preventing an increase in the load of a system and a IP-based network that perform both a process of transmitting information in real time and a process of storing and searching history information and of improving the scalability of the system. A video surveillance system includes: plural cameras that capture images; a monitoring apparatus that displays the images captured by the cameras; an information generating apparatus that generates information for searching the images captured by the cameras; and a search apparatus that searches the images captured by the cameras. The information generating apparatus acquires the images captured by the cameras, generates retrieval data from the acquired images, and transmits the generated retrieval data to the search apparatus. The search apparatus stores the retrieval data received from the information generating apparatus in a storage device, and notifies the monitoring apparatus that the retrieval data has been stored.