A calibration apparatus for executing a camera calibration for each of a plurality of cameras (20, 21, 22, 23) mounted on an object so that image capturing ranges of two of the plurality of cameras overlap each other, the calibration apparatus comprising: an image obtaining unit configured to obtain first and second images captured by the two cameras, the first image including images of a first marker set and a second marker set, the second image including images of the first marker set and a third marker set, each of the first, second and third marker sets including a plurality of markers (P n), a temporary link structure forming unit configured to detect the image of the first marker set of the obtained first image and the image of the first marker set of the obtained second image, form a first line connecting a first representative point which is at a predetermined position in the image of the first marker set in the obtained first image and a second representative point which is at a predetermined position in the image of the second marker set in the obtained first image, form a second line connecting a third representative point which is at a predetermined position in the image of the first marker set in the obtained second image and a fourth representative point which is at a predetermined position in the image of the third marker set in the obtained second image, arrange the lines (LF, LR) so that the first representative point and the third representative point are caused to match each other, and form a temporary link structure including the first and second lines (LF, LR) through the matched first and third representative points and a temporary link angle (α) between the first and second lines; a link angle determining unit configured to determine, as an effective link angle to form an effective link structure from the temporary link structure, the temporary link angle (α) in the case that a difference representing a distance between the images of the same marker of the first marker set in the arranged first and second images is at a minimum; and a parameter determining unit configured to determine parameters for positioning at least one of the cameras on the basis of the effective link angle determined by the link angle determining unit, wherein the respective representative points (M1, M2, M3) each correspond to the barycentric position of the corresponding marker set (10, 11, 12). an image obtaining unit configured to obtain first and second images captured by the two cameras, the first image including images of a first marker set and a second marker set, the second image including images of the first marker set and a third marker set, each of the first, second and third marker sets including a plurality of markers (P n), a temporary link structure forming unit configured to detect the image of the first marker set of the obtained first image and the image of the first marker set of the obtained second image, form a first line connecting a first representative point which is at a predetermined position in the image of the first marker set in the obtained first image and a second representative point which is at a predetermined position in the image of the second marker set in the obtained first image, form a second line connecting a third representative point which is at a predetermined position in the image of the first marker set in the obtained second image and a fourth representative point which is at a predetermined position in the image of the third marker set in the obtained second image, arrange the lines (LF, LR) so that the first representative point and the third representative point are caused to match each other, and form a temporary link structure including the first and second lines (LF, LR) through the matched first and third representative points and a temporary link angle (α) between the first and second lines; a link angle determining unit configured to determine, as an effective link angle to form an effective link structure from the temporary link structure, the temporary link angle (α) in the case that a difference representing a distance between the images of the same marker of the first marker set in the arranged first and second images is at a minimum; and a parameter determining unit configured to determine parameters for positioning at least one of the cameras on the basis of the effective link angle determined by the link angle determining unit, wherein the respective representative points (M1, M2, M3) each correspond to the barycentric position of the corresponding marker set (10, 11, 12).