In order to appropriately perform, in a mobile communication system including a plurality of mobile communication networks respectively operated by a plurality of mobile communication operators, cooperation among respective mobile communication networks, a system 2 includes a control apparatus including a second control unit that performs, via a first mobile communication network 1a operated by a mobile communication operator A, for a second mobile communication network 1b operated by a mobile communication operator B different from the first mobile communication operator A, control related to mobility for a terminal apparatus connected to the second mobile communication network 1b, and a control apparatus including a first control unit that performs, not via another mobile communication network different from the second mobile communication network 1b, for the second mobile communication network 1b, control related to mobility for the terminal apparatus connected to the second mobile communication network 1b.