Surveying Instrument

A surveying instrument includes a distance measuring module for measuring a distance to the object, in which the distance measuring module includes a light projecting optical system configured to project a distance measuring light and a light receiving optical system configured to receive a reflected distance measuring light, the light receiving optical system includes a prism having a quadrangular shape and a photodetector, the prism includes a first plane, a second plane, a third plate and a fourth plane, configured to enter the reflected distance measuring light in the first plane, sequentially internally reflect on the second plane, the first plane, and the third plane, transmit through the fourth plane, and project, and the reflect distance measuring light projected from the prism configured to be received by the photodetector.