Provided is a marker judgment device which has a feature storage means and a feature comparison means. The feature storage means disposes feature points extracted from an image in a predetermined space, sets parts in which the number of feature points in the predetermined space is equal to or less than a predetermined number as singular features, and stores the singular features and feature points extracted from an existing mark. The feature comparison means disposes the feature points extracted from the existing mark in the predetermined space, and judges that the existing mark is capable of being used as a marker which is detectable from the image, when the number of feature points that coincide with the singular features is equal to or more than a predetermined number.
展开▼