1. A marker generation device comprising: a unique feature selector that selects, in a predetermine space in which feature points extracted from an image are displayed, portions of said predetermine space in which the number of said feature points is equal to or less than a predetermined number in a plural number as unique features; and a marker pattern generator that generates plural kinds of marker patterns by employing the whole or one part of said plurality of the unique features, and wherein one unique feature, or two or more to be employed for generating one said marker pattern is defined as a use unique feature group, a plurality of the use unique feature groups for generating plural kinds of said marker patterns are configured of a combination of different unique features, respectively, and when selecting said use unique feature groups in a plural number from among a plurality of the unique features selected by said unique feature selector, said marker pattern generator calculates data of distances related to the unique features constituting said use unique feature groups based upon coordinates of said unique features in said predetermined space, and selects the use unique feature groups to be employed for generating said markers based upon this data of the distances.