The terminal having received the MN RRC reconfiguration message may update source cell configuration information by using a delta scheme when reconfiguration information of the S-SN is in an SN RRC reconfiguration message. In addition, at the same time, the terminal may receive candidate cell IDs, conditions, and pieces of candidate configuration information of T-SNs, and store same in the terminal. After storing configuration information of the candidate cells, the terminal may transfer an RRC reconfiguration complete message to the MN (operation 10-65). The MN having received the message may notify, through an SgNB Modification Confirm message, the S-SN that transfer of sCHO configuration information has succeeded (operation 10-67).