Positional information is provided at a place out of reach of radio wave. The process executed by a positional information providing apparatus includes the steps of: obtaining a received positioning signal; specifying an emission source of the positioning signal; obtaining, when the emission source of the positioning signal is outdoors, a navigation message included in the positioning signal; executing a process for calculating the position based on the signal; obtaining, when the emission source of the positioning signal is indoors, message data from the positioning signal; obtaining coordinate values from the data; and displaying positional information based on the coordinate values.