A position estimation apparatus, a tracker, a position estimation method, and a program which enable estimation of the position or orientation of each of plural trackers in a common coordinate system are provided. A point cloud storage section (80) stores a common point cloud with positions expressed using a common coordinate system. A position estimation section (86) estimates the position or orientation of a first tracker in the common coordinate system on the basis of the common point cloud and first feature point data. The position estimation section (86) estimates the position or orientation of a second tracker in the common coordinate system on the basis of the common point cloud and second feature point data.