In many applications of Augmented Reality (AR), rectangular markers are tracked in real time by capturing with cameras. In this paper, we consider the AR application in which virtual objects are displayed onto markers while the markers and the cameras are freely moving. In this situation, the marker cannot be tracked when the marker is occluded by some objects. In this paper, we propose a method for tracking the projection matrix between the image and the marker even when the maker is occluded, by using cameras. In this method, we transfer the projection matrix for the marker that is detected by the cameras in order to estimate the relative projection matrix for the occluded marker. After computing the relative projection matrices using multiple cameras, we compute a more accurate projection matrix by using particle filter. As a result, we can continuously track the markers even when the marker is occluded.