The present invention comprises an illumination portion (11), which is
disposed in a surveying machine body (8), for illuminating measurement light
toward a reflector (2), a light receiving portion (12), which is
disposed in the surveying machine body (8), having an image sensor for receiving
a reflection light image (M0) of the measurement light illuminated toward
the reflector (2), arithmetic means (37) for calculating a position
in an area (Q2) of the image sensor (27) for the reflection light
image (M0) from the reflector, and a rotation mechanism for rotating the
survey machine body (8) so as to position the reflector (2) on a
light receiving optical axis (O2) of the light receiving portion (12)
based on the position obtained by the arithmetic means (37), and a light
receiving area (Q3) which is a smaller area than the area (Q2) of
the image sensor (27) and has the light receiving optical axis (O2)
as a center is provided in the area (Q2) of the image sensor (27).