A structure is provided in which updating is carried out after setting the presence of updates and an update order according to a priority sequence update setting table 53 when a navigation apparatus 6 carries out incremental updating or comprehensive updating of navigation map data 51 based on incremental update data 28 or comprehensive update data 29 that has been delivered from a map distribution center 2, in particular, even in the case in which updates conflict because the timings for starting the updating processing overlap.