In an optical motion capture system, it is possible to measure spatially high-dense data by increasing the number of measuring points. In the motion capture system using a mesh marker, intersections of lines for the mesh marker are called nodes and the lines connecting the nodes are called edges. The system includes a plurality of cameras for capturing a two-dimensional image of the mesh marker by imaging a subject having the mesh marker, a node/edge detecting section for detecting node/edge information on the mesh marker from the two-dimensional image captured by the respective cameras, and a three-dimensional reconstructing section for acquiring three-dimensional position information of the nodes by using the node/edge information detected from the plurality of two-dimensional images captured by different cameras.