To provide a communication control system and a mobile station control method, in which as soon as a communication in a radio communication system to which a mobile station performed fallback is terminated, the mobile station is quickly returned to a connection with a base station in a radio communication system before the fallback. A RNC 210 includes an information element acquisition unit configured to acquire an information element used to allow the return to a base station before the fallback from an LTE system 10, and a mobile station control unit configured to execute the control to allow the mobile station 300 to return to the HeNB 110. The mobile station control unit executes the control based on the communication state of the mobile station 300 in the 3G system 20.