A base station device comprising: a transmission portion operable to broadcast-transmit, to a mobile terminal in an idle mode under control of the base station device, identification information indicating a first cell in which a load of the base station or of another base station device forming the first cell should be reduced and in which the base station device forming the first cell does not receive a notification of a destination cell; and a reception portion operable to receive information indicating a destination cell that the mobile terminal in the idle mode transmits when moving between cells; wherein the base station device is configured to form a second cell, in which a load does not need to be reduced, adjacent to the first cell, the reception portion is operable to receive information indicating the second cell as the information indicating the destination cell from the mobile terminal in the idle mode which has received the identification information indicating the first cell transmitted from the base station device forming the first cell, and to receive information indicating the first cell as the information indicating the destination cell from the mobile terminal in the idle mode which has received the identification information indicating the first cell transmitted from the base station device (20, 22); wherein the transmission portion is operable to transmit to the mobile terminal a given parameter used when the mobile terminal in the idle mode selects a cell, and the base station device further comprises a changing portion that is operable to change a value of the given parameter based on a number of mobile terminals in the idle mode in the first cell, the number of mobile terminals being calculated with the information indicating the destination cell received from the mobile terminal in the idle mode. a transmission portion operable to broadcast-transmit, to a mobile terminal in an idle mode under control of the base station device, identification information indicating a first cell in which a load of the base station or of another base station device forming the first cell should be reduced and in which the base station device forming the first cell does not receive a notification of a destination cell; and a reception portion operable to receive information indicating a destination cell that the mobile terminal in the idle mode transmits when moving between cells; wherein the base station device is configured to form a second cell, in which a load does not need to be reduced, adjacent to the first cell, the reception portion is operable to receive information indicating the second cell as the information indicating the destination cell from the mobile terminal in the idle mode which has received the identification information indicating the first cell transmitted from the base station device forming the first cell, and to receive information indicating the first cell as the information indicating the destination cell from the mobile terminal in the idle mode which has received the identification information indicating the first cell transmitted from the base station device (20, 22); wherein the transmission portion is operable to transmit to the mobile terminal a given parameter used when the mobile terminal in the idle mode selects a cell, and the base station device further comprises a changing portion that is operable to change a value of the given parameter based on a number of mobile terminals in the idle mode in the first cell, the number of mobile terminals being calculated with the information indicating the destination cell received from the mobile terminal in the idle mode.