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 (S610); specifying an emission source of the positioning signal (S612); obtaining, when the emission source of the positioning signal is outdoors, a navigation message included in the positioning signal (S622); executing a process for calculating the position based on the signal (S624); obtaining, when the emission source of the positioning signal is indoors, message data from the positioning signal (S630); obtaining coordinate values from the data (S632); and displaying positional information based on the coordinate values (S650).