To obtain a method for measuring the position of a tree in which the separation distance can be measured easily through a simple arrangement at a lower cost as compared with a conventional method.

Images of a reference scale 20 having known dimensions and a tree 3 are picked up by means of a digital camera 1 from at least two positions and both images are generalized based on the reference scale 20. Two relative positions are then determined for the reference scale 20 of the tree 3 projected onto the plane of the reference scale 20 in the generalized image. Finally, the position of the tree 3 is calculated based on the relative positional relationship of two relative positions of the tree 3, two image pickup positions and the reference scale 20.