Provided are a method for a connection configuration of a base station including: operating a C-RNTI release timer for release of a C-RNTI which is used in a connection mode before an idle mode after a terminal is transited to the idle mode; and configuring a connection with the terminal by using the C-RNTI before the C-RNTI release timer is expired, a method for connection configuration of a terminal including: receiving information on a release time of a C-RNTI which is used in a connection mode before an idle mode from a base station after being transited to the idle mode; and configuring a connection with the base station by using the existing C-RNTI when a transmission request of uplink data occurs for the release time, and the terminal.