A video distribution method to be carried out in a video distribution system including a user terminal, a bandwidth controller, a Session Initiation Protocol, SIP, session controller, and a video distribution server which are interconnected through an IP network, wherein: said user terminal makes a session establishing request to said SIP session controller based on content information including session information such as a SIP Uniform Resource Identifier, URI, for establishing a session with the video distribution server and meta information such as the title of the content; when said SIP session controller receives said session establishing request, said SIP session controller establishes a session between said user terminal and said video distribution server, and makes a bandwidth securing request for requesting said bandwidth controller to reserve a bandwidth for the distribution of video content in a communication path between said user terminal and said video distribution server; when a session is established between said user terminal and said video distribution server, said bandwidth controller, upon reception of said bandwidth securing request, secures the bandwidth for the distribution of video content in the communication path between said user terminal and said video distribution server; said user terminal makes a request to said video distribution server for starting the video distribution of the requested content, and said video distribution server sends information about a bandwidth required to distribute the requested content to said user terminal; said user terminal or said video distribution server makes a bandwidth changing request for requesting said SIP session controller to change the secured bandwidth for the distribution of video content using said information about a bandwidth required to distribute the requested content; when said SIP session controller receives said bandwidth changing request, said SIP session controller makes a bandwidth changing request for requesting said bandwidth controller to change the previous reserved bandwidth for the distribution of video content which is secured in the communication path between said user terminal and said video distribution server to the bandwidth required to distribute the requested content; and when said bandwidth controller receives said bandwidth changing request, said bandwidth controller changes the bandwidth which is secured in the communication path between said user terminal and said video distribution server to the requested bandwidth. said user terminal makes a session establishing request to said SIP session controller based on content information including session information such as a SIP Uniform Resource Identifier, URI, for establishing a session with the video distribution server and meta information such as the title of the content; when said SIP session controller receives said session establishing request, said SIP session controller establishes a session between said user terminal and said video distribution server, and makes a bandwidth securing request for requesting said bandwidth controller to reserve a bandwidth for the distribution of video content in a communication path between said user terminal and said video distribution server; when a session is established between said user terminal and said video distribution server, said bandwidth controller, upon reception of said bandwidth securing request, secures the bandwidth for the distribution of video content in the communication path between said user terminal and said video distribution server; said user terminal makes a request to said video distribution server for starting the video distribution of the requested content, and said video distribution server sends information about a bandwidth required to distribute the requested content to said user terminal; said user terminal or said video distribution server makes a bandwidth changing request for requesting said SIP session controller to change the secured bandwidth for the distribution of video content using said information about a bandwidth required to distribute the requested content; when said SIP session controller receives said bandwidth changing request, said SIP session controller makes a bandwidth changing request for requesting said bandwidth controller to change the previous reserved bandwidth for the distribution of video content which is secured in the communication path between said user terminal and said video distribution server to the bandwidth required to distribute the requested content; and when said bandwidth controller receives said bandwidth changing request, said bandwidth controller changes the bandwidth which is secured in the communication path between said user terminal and said video distribution server to the requested bandwidth.