1. A position/orientation measurement method for calculating a position and orientation of an object, comprising: a subjective viewpoint image acquisition step of acquiring a first image obtained by capturing a scene by a subjective viewpoint image sensing unit attached to the object; an objective viewpoint image acquisition step of acquiring a second image obtained by capturing an image of the object by an objective viewpoint image sensing unit; a first detection step of detecting a feature value associated with an image coordinate of a first indicator arranged in the scene from the first image; a second detection step of detecting a feature value associated with an image coordinate of a second indicator arranged on the object or the objective viewpoint image sensing unit from the second image; and a position/orientation calculation step of calculating the position and orientation of the object using the feature value associated with the image coordinate of the first indicator detected in the first detection step and the feature value associated with the image coordinate of the second indicator detected in the second detection step.