PURPOSE: To make it possible to compute the distance and the latitude and the longitude of a point on a map by providing a scale, on which specified diminishing scale graduations are marked, on the main body of a GPS, and displaying the angle per degree on the scale.

CONSTITUTION: A scale 2 is provided at the corner part of the edge of a GPS main body 1. A diminishing scale graduation 3 of AKm per degree in, e.g. a scale of 1/10,000 and an angle X° Y' Z" per degree of the graduation 3 are marked on the scale 2. The scale is applied on a map. When the number of the graduation read between two points is 7, the distance is computed as 7×AKm in the case of the map of the same scale. Furthermore, the angle X° Y' Z" per degree of the scale is used, and the number of the graduations from the reference point of the map, where the latitude and the longitude are known, is read. The number is multiplied by the angle X° Y' Z". The obtained value is added to the latitude of the reference point and subtracted from the longitude of the reference point. Thus, the latitude and the longitude of the objective point can be computed.