A surveying system , having a surveying instrument comprising a first surveying unit which projects a distance measuring light and measures a prism , a second surveying unit provided integrally with said first surveying unit, and an arithmetic control module , and a target instrument installed at a measuring point , wherein said first surveying unit comprises a frame in a horizontally rotatable manner, a telescope unit provided on said frame in a vertically rotatable manner, a first angle measuring unit which detects a horizontal angle of said frame and a vertical angle of said telescope unit, and a first distance measuring unit which is accommodated in said telescope unit and measures a distance to said prism, wherein said second surveying unit comprises a scanning mirror which rotatably irradiates a laser beam to one axis in a vertical direction or a horizontal direction and a second angle measuring unit which detects a vertical angle of said scanning mirror, wherein said target instrument comprises a pole , said prism provided on an axis of said pole and has a known positional relationship with a lower end of said pole, and a target plate mounted on said pole, wherein said target plate is two or more plate materials provided at an equal angular interval radially on said pole , said prism is an omnidirectional prism provided on an upper end of said target plate, and wherein said arithmetic control module scans a laser beam by a cooperative operation of the horizontal rotation of said frame or the vertical rotation of said telescope unit and the vertical rotation or the horizontal rotation of said scanning mirror, acquires point cloud data of adjacent two surfaces of said target plate, calculates a ridge line formed by said two surfaces crossing each other based on measurement results of said two surfaces of said target plate obtained from said point cloud data as said measuring point direction vector , and calculates a three-dimensional coordinate of said measuring point based on the three-dimensional coordinate of an optical center of said prism measured by said first measuring unit, said measuring point direction vector, and the positional relationship between the optical center of said prism and the lower end of said pole. wherein said target plate is two or more plate materials provided at an equal angular interval radially on said pole , said prism is an omnidirectional prism provided on an upper end of said target plate, and wherein said arithmetic control module scans a laser beam by a cooperative operation of the horizontal rotation of said frame or the vertical rotation of said telescope unit and the vertical rotation or the horizontal rotation of said scanning mirror, acquires point cloud data of adjacent two surfaces of said target plate, calculates a ridge line formed by said two surfaces crossing each other based on measurement results of said two surfaces of said target plate obtained from said point cloud data as said measuring point direction vector , and calculates a three-dimensional coordinate of said measuring point based on the three-dimensional coordinate of an optical center of said prism measured by said first measuring unit, said measuring point direction vector, and the positional relationship between the optical center of said prism and the lower end of said pole. <EOS>