A radio communication system comprising: base stations (eNB, TP) that are identifiable by their respective identifiers; a user device configured to perform radio communication with each of the base stations; and a communication control device (PhNB) configured to control radio communication between the base stations (eNB, TP) and the user device, the user device comprising: a level measuring unit configured to measure received levels of radio waves transmitted from the base stations; and a storage unit configured to store a first list and a second list, the first list comprising identifiers of base stations (eNB, TP) that are wirelessly communicable with the user device, the identifiers having been acquired by synchronization acquisition, the second list comprising identifiers of base stations (eNB, TP) with which the user device should maintain synchronization, the communication control device (PhNB) comprising: a selection information generating unit configured to generate selection information that is used to select base stations (eNB, TP) with which the user device should maintain synchronization; and a selection information reporting unit configured to report the selection information to the user device, the user device further comprising: a base station selecting unit configured to select, based on the selection information reported by the communication control device, base stations (eNB, TP) with which the user device should maintain synchronization from among base stations corresponding to the identifiers comprised in the first list so as to store identifiers of the selected base stations (eNB, TP) in the second list; a base station information reporting unit configured to report, to the communication control device, the identifiers of the base stations (eNB, TP) selected by the base station selecting unit, the identifiers being comprised in the second list, and received levels of radio waves transmitted from the base stations (eNB, TP) corresponding to the identifiers; and a synchronization maintaining unit configured to maintain synchronization with each of the base stations (eNB, TP) corresponding to the identifiers comprised in the second list, wherein the level measuring unit of the user device is configured to measure received levels of radio waves transmitted from each of the base stations (eNB, TP) corresponding to the identifiers comprised in the first list, wherein the selection information generating unit of the communication control device (PhNB) is configured to generate, as the selection information, a maximum number of the identifiers that the second list is allowed to comprise, wherein the user device further comprises a determining unit configured to determine, based on a state of the user device, a maximum number of the identifiers that the second list is allowed to comprise, and wherein the base station selecting unit of the user device is configured to select, as the base stations (eNB, TP) with which the user device should maintain synchronization, base stations (eNB, TP) up to a number that is lesser of the maximum number of the identifiers indicated by the selection information and the maximum number of the identifiers determined by the determining unit in descending order of the received levels measured by the level measuring unit. base stations (eNB, TP) that are identifiable by their respective identifiers; a user device configured to perform radio communication with each of the base stations; and a communication control device (PhNB) configured to control radio communication between the base stations (eNB, TP) and the user device, a level measuring unit configured to measure received levels of radio waves transmitted from the base stations; and a storage unit configured to store a first list and a second list, the first list comprising identifiers of base stations (eNB, TP) that are wirelessly communicable with the user device, the identifiers having been acquired by synchronization acquisition, the second list comprising identifiers of base stations (eNB, TP) with which the user device should maintain synchronization, the first list comprising identifiers of base stations (eNB, TP) that are wirelessly communicable with the user device, the identifiers having been acquired by synchronization acquisition, the second list comprising identifiers of base stations (eNB, TP) with which the user device should maintain synchronization, a selection information generating unit configured to generate selection information that is used to select base stations (eNB, TP) with which the user device should maintain synchronization; and a selection information reporting unit configured to report the selection information to the user device, a base station selecting unit configured to select, based on the selection information reported by the communication control device, base stations (eNB, TP) with which the user device should maintain synchronization from among base stations corresponding to the identifiers comprised in the first list so as to store identifiers of the selected base stations (eNB, TP) in the second list; a base station information reporting unit configured to report, to the communication control device, the identifiers of the base stations (eNB, TP) selected by the base station selecting unit, the identifiers being comprised in the second list, and received levels of radio waves transmitted from the base stations (eNB, TP) corresponding to the identifiers; and a synchronization maintaining unit configured to maintain synchronization with each of the base stations (eNB, TP) corresponding to the identifiers comprised in the second list,