An optical tracking system comprising a marker part configured to include a pattern that has particular information and a first lens that is spaced apart from the pattern and has a first focal length; a first image forming part configured to include a second lens that has a second focal length and a first image forming unit that is spaced apart from the second lens and on which a first image of the pattern is formed by the first lens and the second lens; and a second image forming part configured to include a third lens that has a third focal length and a second image forming unit that is spaced apart from the third lens and on which a second image of the pattern is formed by the first lens and the third lens, wherein the optical tracking system comprises a processing part configured to: calculate a first posture definition matrix from a first coordinate conversion formula and a second coordinate conversion formula, wherein the first coordinate conversion formula is defined to convert a coordinate on a pattern surface of the pattern to a first pixel coordinate on the first image of the pattern of the first image forming part, and includes conversion matrices and a first posture definition matrix that defines a posture of the marker part with respect to the first image forming part, wherein the second coordinate conversion formula is defined to convert a coordinate on the pattern surface of the pattern to a second pixel coordinate on the second image of the pattern of the second image forming part, and includes conversion matrices and a second posture definition matrix that defines the posture of the marker part with respect to the second image forming part, the second posture definition matrix is a product of the first posture definition matrix and a third posture definition matrix that defines a posture of the first image forming part with respect to the second image forming part to convert the first pixel coordinate to the second pixel coordinate, determine the posture of the marker part from the first posture definition matrix; and track the marker part based on the determined posture of the marker part, wherein a distance between the first lens and the pattern is the same as the first focal length, a distance between the first image forming unit and the second lens is the same as the second focal length, and a distance between the second image forming unit and the third lens is the same as the third focal length. calculate a first posture definition matrix from a first coordinate conversion formula and a second coordinate conversion formula, wherein the first coordinate conversion formula is defined to convert a coordinate on a pattern surface of the pattern to a first pixel coordinate on the first image of the pattern of the first image forming part, and includes conversion matrices and a first posture definition matrix that defines a posture of the marker part with respect to the first image forming part, wherein the second coordinate conversion formula is defined to convert a coordinate on the pattern surface of the pattern to a second pixel coordinate on the second image of the pattern of the second image forming part, and includes conversion matrices and a second posture definition matrix that defines the posture of the marker part with respect to the second image forming part, the second posture definition matrix is a product of the first posture definition matrix and a third posture definition matrix that defines a posture of the first image forming part with respect to the second image forming part to convert the first pixel coordinate to the second pixel coordinate, determine the posture of the marker part from the first posture definition matrix; and track the marker part based on the determined posture of the marker part, wherein a distance between the first lens and the pattern is the same as the first focal length, a distance between the first image forming unit and the second lens is the same as the second focal length, and a distance between the second image forming unit and the third lens is the same as the third focal length.