Surveying Instrument

A surveying instrument comprises a monopod installed at a reference point, a surveying instrument main body provided at the monopod and having an attitude detector, wherein the surveying instrument main body carries out an image pickup and a scanning of an object to be measured at a pre-movement and a post-movement respectively, obtains at least three cross points of a locus of a scan pattern of the pre-movement and the post-movement, and calculates three-dimensional coordinates of an installation point of the post-movement based on three-dimensional coordinates of the cross points measured from the reference point, a measurement result of the cross points measured from the installation point of the post-movement and a detection result of the attitude detector.