Surveying Instrument

A surveying instrument comprises a monopod installed on a reference point, a surveying instrument main body having a reference optical axis and an operation panel, wherein the surveying instrument main body has a distance measuring unit, an arithmetic control module, a measuring direction image pickup module which acquires a first image, and an attitude detector which detects tilts of two axes of the surveying instrument main body to the horizontal, and wherein the operation panel has a display unit, a calculating module, and as operation module, and the at least either one of the arithmetic control module and the calculating module calculates a tilt angle of the reference optical axis to the horizontal and a tilt angle of the monopod to the vertical, and the at least either one measures a horizontal distance and a vertical distance to the object to be measured with reference to the reference point.