A storage unit stores therein setting information and history information on a communication established by the setting information. When an information receiving unit receives new setting information, a judging unit judges whether the setting information stored in the storage unit reached a predetermined value. A determining unit compares the history information corresponding to the setting information, and determines a priority for each setting information based on a result of comparison. A deleting unit deletes setting information having the lowest priority from the storage unit, and a storing unit stores the new setting information in the storage unit.