Firstly, a template image is created (S501). Then, an image I.sup.t is photographed (S502). And the sensor output is acquired (S503). A model view matrix M.sup.t is calculated on the basis of the sensor output (S504). And a correction matrix .DELTA.M.sup.t is calculated (S505). And the model view matrix M.sup.t is corrected employing the calculated correction matrix .DELTA.M.sup.t (S506). Then CG is drawn and displayed using the corrected model view matrix (S507).