An optical tracking system comprises a marker part, an image forming part, and a processing part. The marker part includes a pattern having particular information and a first lens which is spaced apart from the pattern and has a first focal length. The image forming part includes a second lens having a second focal length and an image forming unit which is spaced apart from the second lens and forms an image of the pattern by the first lens and the second lens. The processing part determines the posture of the marker part from a coordinate conversion formula between a coordinate on the pattern surface of the pattern and a pixel coordinate on the image of the pattern, and tracks the marker part by using the determined posture of the marker part. Therefore, the present invention can accurately track a marker part by a simpler and easier method.