1. A position and orientation determination method for identifying a parameter indicating position and orientation of image sensing means for performing image sensing on actual space, in which plural feature points exist in already-known three-dimensional positions, comprising: a measurement step of measuring the position and orientation of said image sensing means by a method other than utilization of video image obtained by image sensing by said image sensing means, and obtaining a first parameter indicating the position and orientation of said image sensing means; and a correction step of correcting said first parameter obtained at said measurement step based on said plural feature points in the video image of said actual space obtained by said measurement unit, and identifying a second parameter indicating the position and orientation of said image sensing means, wherein at said correction step, said first parameter is corrected by rotation of said image sensing means about a visual axis, based on said plural feature points in said video image.