In a case where a CPU 11 provided in an information distribution center 3 has received a request command for requesting predicted traffic information transmitted from a navigation apparatus 2 as well as vehicle information such as a navigator identifying ID, coordinate data of a vehicle position, or coordinate data of a destination, the CPU 11 searches a basic route based on update-purpose map information 14A, and sets a distribution range serving as a transmission target of traffic information 16A, 16H, and 16C. Then, the CPU 11 generates the predicted traffic information 16C such as congestion prediction information corresponding to the distribution range, extracts the predicted traffic information 16C of each link having a difference in the generated predicted traffic information 16C and the current traffic information 16A, and distributes the extracted predicted traffic information 16C to the navigation apparatus 2 together with a link ID of a corresponding link.