1. A position and orientation measurement apparatus comprising: at least one memory storing computer executable instructions; and at least one processor configured to execute the computer executable instructions to implement: an acquisition unit configured to acquire, from an image including a target object, at least one coarse position and orientation of the target object, wherein the coarse position and orientation is acquired based on a predetermined resolution; a generation unit configured to generate, based on the acquired coarse position and orientation and the predetermined resolution, at least one candidate position and orientation which is different from the coarse position and orientation; and a deriving unit configured to derive a position and orientation of the target object in the image based on the generated position and orientation and model information of the target object.