This invention is to cope with users requesting the delivery of stream data, flexibly. In this invention, a user terminal requesting the delivery of the stream data is used as a node in a delivery tree whose root is a delivery source device connected to a camera, and relays the stream data to a lower stage. This delivery tree is managed by a delivery management server. Then, it executes: receiving a delivery request of specific stream data; identifying an apparatus whose number of stages from the root of the delivery tree is the least and having a remaining relay resource with reference to a delivery management database storing the number of stages from the root of the delivery tree, data representing a remaining relay resource and access destination data for each of apparatuses including a root device of the delivery tree and terminals as nodes in the delivery tree; and reading out the access destination data of the identified apparatus from the delivery management database, and transmitting the read access destination data as request destination data of the specific stream data to the delivery requesting terminal.