A wireless connecting method includes a connection monitoring step, a connection parameter retaining step, and a connection restoring step. The connection monitoring step monitors the wireless connection between the communication terminal device and the base station. The connection parameter retaining step sets a communication session retention time period that is longer than a connection parameter retention time period, and retains a connection parameter. A connection parameter when the wireless connection is disconnected is retained in at least one of the communication terminal device and the base station for the communication session retention time period exceeding the connection parameter retention time period. The connection restoring step executes, after the connection parameter retention time period has elapsed, when the communication session retention time period has not elapsed, an initial connecting process and restores the connection using the connection parameter stored when the wireless connection is disconnected.