1. A method for managing data by using a computer, the method comprising: accepting a registration request of polygon data including data pertaining to a latitude and a longitude of each vertex of a polygon; specifying a minimum unit rectangle that matches a minimum bounding rectangle of the polygon or includes the minimum bounding rectangle from a plurality of unit rectangles, the plurality of unit rectangles formed by recursively dividing a two-dimensional space including a latitude/longitude range, the two-dimensional space being equally divided in an X direction and a Y direction in the same number; generating a character string by assigning values indicating latitude and longitude to the identified minimum unit rectangle or all unit rectangles including the identified minimum unit rectangle in correspondence with the number of divided parts of the two-dimensional space in the X and Y directions, and alternately arranging the assigned values, in the X direction or the Y direction, in a descending order starting from values corresponding to a large unit rectangle among the plurality of unit rectangles; and storing the polygon data in correspondence with a key including the character string in a storage unit, wherein a size of each of the plurality of unit rectangles becomes smaller in correspondence with the descending order.