Provided is a surveying instrument including a distance measuring module configured to measure a distance to an object, an optical axis deflector configured to deflect the distance measuring light, a measuring direction image pickup module configured to acquire an observation image, an arithmetic control module, and an operation panel includes a display module, the arithmetic control module is configured to cause the optical axis deflector to perform a scan with a predetermined scan pattern and create an overlay image as a superimposition of the locus of the scan pattern on the observation image, and calculate a formula of a straight line or a curve line based on a measurement result of intersections or the closest points to the intersections between the straight line or the curve line drawn along a ridge line or a contour of the object and the locus of the scan pattern on the displayed overlay image.