A position and orientation measurement apparatus for measuring the position and orientation of a target object includes a first search unit which searches a geometric model for a lost model region corresponding to a lost image region in a range image, a determination unit which determines whether or not a point on a geometric model corresponding to a pixel on the range image of the target object falls within the lost model region, a correction unit which corrects combinations of pixels on the range image and corresponding points which are determined to fall within the lost model region, and a calculation unit which calculates the position and orientation of the target object based on the corrected combinations of the pixels on the range image and points on the geometric model.