Patent ID: 8140254

Claim:
A navigation apparatus for navigating using navigating-use road map data that is road map data for navigating, the navigation apparatus comprising: a CPU; a reader that reads a reduced road map data from a first storage medium that stores the reduced road map data, the reduced road map data is a road map data prepared by applying a deletion rule to a primary navigating-use road map data, the primary navigating-use road map data has a primary data configuration state that contains a plurality of data frames, each data frame containing (i) a management field where management information is stored, and (ii) a record portion having at least one record, the management field defines a record number indicating a number of records stored in the record portion, the deletion rule (i) specifies an unused data area, which stores no data in each record, based on the record number of the management field and (ii) deletes the specified unused data area in the data frames included in the primary data configuration state of the primary navigating-use road map data; and a storage device that previously records restoration information on a restoration rule that pairs with the deletion rule while taking action opposite to the deletion rule, the CPU including a restorer configured to execute the restoration rule which is indicated based on the recorded restoration information to the read reduced road map data, when the reduced road map data is read from the first storage medium by the reader, the restoration rule configured to read the reduced road map data which (i) specifies an unused data area, which was deleted in the deletion rule and (ii) restores the specified unused data area in a state identical to a state of the unused data area deleted in the deletion rule, to generate a navigating-use road map data, such that a data configuration state of the generated navigating-use road map data is identical to the primary data configuration state of the primary navigating-use road map data.