A radio network controller (1) to be connected to a mobile terminal via a radio base station comprises: holding means (UE check list 15 for each system) for, when each mobile terminal has failed to make a radio connection to a cell (s) selected by a cell selection algorithm that assigns a cell (s) under the radio base station to the mobile terminal, holding information of the cell (s) to which the mobile terminal has failed to make a radio connection, for a predetermined period; and execution means (cell selection processor 11) for excluding a cell (s) to which the mobile terminal has failed a radio connection once in the past, from adjacent cell candidates of said mobile terminal, based on the cell information held by the holding means, for a predetermined period, and to execute the cell selection algorithm.