Three pieces of candidate position information are calculated based on a plurality of pieces of sensing position information, and three pieces of candidate orientation information are calculated based on a plurality of pieces of sensing orientation information. Sets each of which combines one candidate position information and one candidate orientation information are prepared for all combinations. For each set, the candidate position information and candidate orientation information which configure that set are corrected. An evaluation value is calculated for each corrected set, and one of the sets is selected based on the calculated evaluation values. The candidate position information and candidate orientation information which configure the selected set are respectively recorded in a memory as sensing position information and sensing orientation information.