A surveying apparatus is provided that includes a sighting telescope, an imaging device, and an external orientation parameter calculator. The sighting telescope is rotatable about a horizontal axis and a vertical axis. The imaging device is integrally rotated with the sighting telescope and the imaging device has an optical axis that is different from the collimation axis. The external orientation parameter calculator calculates external orientation parameters of stereo images that are obtained by the imaging device in an erecting observation and in an inverse observation in terms of the position of the optical axis with respect to the collimation axis, and the sighting directions in the erection observation and in the inverse observation.