The present invention relates to a mobile communication system comprising a structure for realizing “network seamless” for roaming between different kinds of networks, “contents seamless” for converting different kinds of encoding or media therebetween, and “device seamless” for making it possible to utilize optimum I/O devices in conformity to surrounding environments. This mobile communication system detects a change in an environment in use concerning an object such as a mobile terminal, for example, notifies at least one apparatus relating to the change of the result of detection, sets various resources constituting a network in conformity to a new environment, and switches them. This makes it possible to construct a seamless network which automatically eliminates seams (restrictions) concerning changes in the environment and the like.