A surveying instrument including a light projecting optical system which projects the distance measuring light, a light receiving optical system which receives the reflected distance measuring light from an object, a frame unit 5 which horizontally rotates around a horizontal rotation shaft, a scanning mirror which is provided in the frame unit, vertically rotates, a horizontal angle detector which detects a horizontal angle of the frame unit, a vertical angle detector which detects a vertical angle of the scanning mirror and an arithmetic control module which calculates the three-dimensional coordinates of the object, in which the light receiving optical system has a reflecting mirror having a reflecting surface which is an off-axis paraboloidal surface or an off-axis free-form surface, and the reflected distance measuring light is configured to be led to a light receiving module by the reflecting mirror while being condensed.