The present invention provides a method and apparatus for inputting a signal indicating a change in position of an image sensing apparatus to predict present position and orientation of the image sensing apparatus using previously obtained position and orientation, by identifying corresponding pairs of indicators detected from an image in real space sensed by the image sensing apparatus and indicators contained in an image when sensed from a predicted position and orientation and using a correction method determined by the number of identified indicator pairs either to correct all or some of the degrees of freedom of the predicted camera position and orientation or to use the predicted camera position and orientation directly as is. As a result, highly accurate detection results can be obtained using a simple structure in the detection of the position and orientation of the image sensing apparatus.