PROBLEM TO BE SOLVED: To extract a tree which may be highly possibly influenced by land development accompanied by tree lumbering and construction of structures before the land development is carried out. SOLUTION: A structure distance calculating means 151 calculates the distance between a tree and a structure from numerical map data of an object area which is extracted by an area extracting means 130 and stored in a numerical map data storage means 111, the position, requested to be inputted by a tree planting position data input request means 121a of a tree data input request means 121, where the tree is planted, the attribute of the tree requested to be inputted by a tree attribute data input request means 121b, and the position, requested to be inputted by a structure position data input request means 122a, where the structure is constructed. Based upon the calculation result, a tree extracting means 160 extracts the tree. COPYRIGHT: (C)2004,JPO
