A navigation device that is configured to operate according to a plurality of application programs including at least a first program ( AP1, AP2) and a second program, reference map data of a reference data format referred to by the application programs being updatable, the navigation device being characterized in that it comprises: a conversion unit that is adapted to convert data in a predetermined update data format into data in the reference data format; and a reference map data update unit that is adapted to update the reference map data with the data in the reference data format after conversion by the conversion unit; wherein the reference map data is formed of a common map data frame commonly referred to by the plurality of application programs, a first map data frame referred to by the first program ( AP1, AP2), and a second map data frame referred to by the second program; and the data in the update data format is divided into data frames (F10-F16), wherein each data frame stores data of a certain data type, and wherein each data frame stores at least one of: a first group of one or more common map data records ( A01, A02,...) to be stored according to the data type of the respective data frame in the common map data frame after conversion by the conversion unit; a second group of one or more first map data records ( B01, B02,...) to be stored according to the data type of the respective data frame in the first map data frame after conversion by the conversion unit; and a third group of one or more second map data records ( C01, C02,...) to be stored according to the data type of the respective data frame in the second map data frame after conversion by the conversion unit; and wherein data stored in the common map data frame includes data relating to a road network formed by at least one link and one node, and is commonly referred to by the plurality of application programs. a conversion unit that is adapted to convert data in a predetermined update data format into data in the reference data format; and a reference map data update unit that is adapted to update the reference map data with the data in the reference data format after conversion by the conversion unit; wherein the reference map data is formed of a common map data frame commonly referred to by the plurality of application programs, a first map data frame referred to by the first program ( AP1, AP2), and a second map data frame referred to by the second program; and the data in the update data format is divided into data frames (F10-F16), wherein each data frame stores data of a certain data type, and wherein each data frame stores at least one of: a first group of one or more common map data records ( A01, A02,...) to be stored according to the data type of the respective data frame in the common map data frame after conversion by the conversion unit; a second group of one or more first map data records ( B01, B02,...) to be stored according to the data type of the respective data frame in the first map data frame after conversion by the conversion unit; and a third group of one or more second map data records ( C01, C02,...) to be stored according to the data type of the respective data frame in the second map data frame after conversion by the conversion unit; and a first group of one or more common map data records ( A01, A02,...) to be stored according to the data type of the respective data frame in the common map data frame after conversion by the conversion unit; a second group of one or more first map data records ( B01, B02,...) to be stored according to the data type of the respective data frame in the first map data frame after conversion by the conversion unit; and a third group of one or more second map data records ( C01, C02,...) to be stored according to the data type of the respective data frame in the second map data frame after conversion by the conversion unit; and wherein data stored in the common map data frame includes data relating to a road network formed by at least one link and one node, and is commonly referred to by the plurality of application programs.