1. A position/orientation determination method for determining a position and an orientation of a target object, the method comprising: an image input step of inputting a shot image obtained from an imaging device attached to the target object; an orientation input step of inputting a measured orientation obtained from an orientation sensor which acquires information regarding the orientation of the target object; a feature detection step of obtaining feature values regarding image coordinates of indices arranged on a scene from the shot image as measured feature values; and a calculation step of calculating parameters for determining the position and the orientation of the target object, the parameters being calculated such that errors between the measured feature values being obtained in the feature detection step and their theoretical values being obtained on the basis of the measured orientation and estimated parameters are reduced, using image Jacobians of the theoretical feature values with respect to the parameters.