A method of determining a position and pose of a marker with respect to a camera, the marker including: a quadrilateral; a first circle group including a plurality of first circles (C1-C5), centers of the first circles being within the quadrilateral and present in a line of a first diagonal which is one of two diagonals of the specified quadrilateral; a second circle group including a plurality of second circles (C6-C9, C3), centers of the second circles being within the quadrilateral and present in a line of a second diagonal which is the other diagonal of the two diagonals; and a direction-identification circle, wherein the first circle group and the second circle group are formed so as to have point symmetry with respect to the intersection (C3P) of the line of the first diagonal and the line of the second diagonal, the direction-identification circle is positioned such that point symmetry of a group of circles consisting of the first circle group, the second circle group and the direction-identification circle with respect to the intersection (C3P) is broken, and the direction-identification circle is positioned on a triangle formed with the intersection (C3P) by two adjacent vertexes (P2, P3) of the quadrilateral, and no direction-identification circle is positioned on the other triangles formed with the intersection (C3P) by the other pairs of adjacent vertexes (P0-P1, P1-P2, P3-P0) of the quadrilateral, the method comprising: capturing an external scenery using a camera; extracting the marker from an image of the captured external scenery; identifying the direction-identification circle; identifying each circle (C1-C9) in the first circle group and the second circle group from the extracted marker; and calculating a position and pose of the marker with respect to the camera based on the identified direction-identification circle, first circles (C1-C5) and second circles (C6-C9, C3). a quadrilateral; a first circle group including a plurality of first circles (C1-C5), centers of the first circles being within the quadrilateral and present in a line of a first diagonal which is one of two diagonals of the specified quadrilateral; a second circle group including a plurality of second circles (C6-C9, C3), centers of the second circles being within the quadrilateral and present in a line of a second diagonal which is the other diagonal of the two diagonals; and a direction-identification circle, wherein the first circle group and the second circle group are formed so as to have point symmetry with respect to the intersection (C3P) of the line of the first diagonal and the line of the second diagonal, the direction-identification circle is positioned such that point symmetry of a group of circles consisting of the first circle group, the second circle group and the direction-identification circle with respect to the intersection (C3P) is broken, and the direction-identification circle is positioned on a triangle formed with the intersection (C3P) by two adjacent vertexes (P2, P3) of the quadrilateral, and no direction-identification circle is positioned on the other triangles formed with the intersection (C3P) by the other pairs of adjacent vertexes (P0-P1, P1-P2, P3-P0) of the quadrilateral, the method comprising: capturing an external scenery using a camera; extracting the marker from an image of the captured external scenery; identifying the direction-identification circle; identifying each circle (C1-C9) in the first circle group and the second circle group from the extracted marker; and calculating a position and pose of the marker with respect to the camera based on the identified direction-identification circle, first circles (C1-C5) and second circles (C6-C9, C3). capturing an external scenery using a camera; extracting the marker from an image of the captured external scenery; identifying the direction-identification circle; identifying each circle (C1-C9) in the first circle group and the second circle group from the extracted marker; and calculating a position and pose of the marker with respect to the camera based on the identified direction-identification circle, first circles (C1-C5) and second circles (C6-C9, C3).