A mobile communication terminal 10 is configured to transmit a control signal indicating a request for cell reselection to the second communication system to the first communication system before a communication resource of the second communication system is reserved while the mobile communication terminal was located in the first communication system. The first communication system releases a communication resource of the first communication system in response to the control signal indicating the request for cell reselection to the second communication system even before the communication resource of the second communication system is reserved.