A mobile communication system capable of executing optimization of network processing based on a change in utilization characteristics is provided. The mobile communication system according to the present invention includes a network operator device (12) that is arranged in a mobile communication network managed by a mobile communication provider and a service platform (13) that provides an application service for a mobile communication device (11), the mobile communication device performing communication via the mobile communication network. The service platform (13) transmits to the network operator device (12) a characteristic change in the mobile communication device (11) associated with an event notification transmitted from the mobile communication device (11) and the network operator device (12) changes a network parameter associated with the mobile communication device (11) according to the characteristic change in the mobile communication device (11) transmitted from the service platform (13).