Device for map information processing and position display

A terminal unit (400) acquires navigation electric wave, generates an assumed coordinate information, and transmits the information to a position information processing device (320) over a network (200), so that the position information processing device (320) generates a position information on the current position of the terminal unit (400) and an accuracy information on a positioning accuracy. The terminal unit (400) acquires the position information and the accuracy information from the position information processing device (320) and transmits them to a server unit (500) over the network (200) with information on a display area where a map is displayed. The server unit (500) sets a scale rate of the map based on the accuracy information and calculates a circular area where the terminal unit (400) may be located. The server unit (500) reads a map information of the circular area, the diameter of which is 80% of the short dimension of the display area, and transmits the information to the terminal unit (400) for displaying it. An error area can be displayed in detail.