1. A position and orientation measurement apparatus comprising: a storage unit configured to store information of a three-dimensional shape model of a target object; a distance information obtaining unit configured to obtain distance information of the target object captured by a capturing unit; an image obtaining unit configured to obtain a two-dimensional image of the target object captured by the capturing unit; a first position and orientation estimation unit configured to estimate a first estimated value representative of the position and orientation of the target object based on the information of the three-dimensional shape model stored in said storage unit and the distance information; a second position and orientation estimation unit configured to estimate a second estimated value representative of the position and orientation of the target object based on a geometric feature of the two-dimensional image and projection information obtained by projecting, on the two-dimensional image, the information of the three-dimensional shape model stored in said storage unit; and a determination unit configured to determine whether a parameter of the capturing unit needs to be calibrated, based on both the first estimated value estimated by said first position and orientation estimation unit and the second estimated value estimated by said second position and orientation estimation unit.