To provide a device and a method for enabling a connection to an alternative line before the detection of congestion and avoiding the delay of communication even when the communication load is heavy.

This device is provided with a statistic part 15 for collecting the statistic use conditions of the alternative line and a congestion monitoring part 14 for outputting an alternative connecting instruction to a line selecting part 13 when the line congestion of a leased line communication control part 11 is detected and the line selecting part having received the alternative connecting instruction outputs the alternative connecting instruction to an alternative line communication control part 12 so that the line congestion of the leased line communication control part can be avoided. The statistic part is provided with an alternation monitoring means for monitoring the use condition of the alternative line communication control part, a database part 153 for storing information collected by the alternation monitoring means and an alternation judgement means for instructing the connection of the alternative line on the basis of information on the database part and when it is confirmed that the time zone where the alternative line communication control part is connected is concentrated in a certain period, before the congestion monitoring part detects the congestion, the alternative connection instruction is outputted to the line selecting part.