Highly-accurate approximate positional information is transmitted to a communication terminal. An approximate positional information database of a server included in a positioning support system includes approximate positional information used for positioning calculation at the communication terminal and which indicates a position of a cell in which the communication terminal is located and a cell identifier identifying the cell, with approximate positional information and the cell being associated with each other. Based on a positioning information transmission request which includes a cell and which is transmitted from the communication terminal, approximate positional information stored in the approximate positional information database is acquired and transmitted from a communication unit to the communication terminal. Positioning result information indicating a result of the positioning calculation transmitted from the communication terminal is received and, based on this information, approximate positional information stored in the approximate positional information database is updated by a control unit. The accuracy of approximate positional information is enhanced due to the approximate positional information stored in the approximate positional information database being updated based on positioning result information.