From a sequence of images captured by an image pickup unit, images necessary for measuring placement information regarding markers and/or a sensor are automatically determined and obtained. To this end, using position and orientation information regarding the image pickup unit at the time the image pickup unit has captured an obtained image and placement information regarding detected markers, whether to use the captured image corresponding to the position and orientation is determined. Using the captured image determined to be used, the marker placement information, placement information regarding a measurement target, or the position and orientation of the image pickup unit serving as an unknown parameter is obtained so as to minimize the error between the measured image coordinates and theoretical image coordinates of each marker, which are estimated on the basis of a rough value of the parameter.