A deflecting device and a surveying instrument for deflecting an optical axis two-dimensionally comprising a ring-shaped holding member; ring gears disposed on both sides of the holding member with the holding member interposed between the ring gears and concentric with the holding member; rotary bearings disposed between the holding member and the ring gears on both sides of the holding member and concentric with the holding member; optical deflecting members disposed at central portions of the ring gears and integrated with the ring gears; deflection motors corresponding to the respective ring gears; a drive transmitting member configured to transmit rotary force of the deflection motors to the ring gears; and urging members configured to urge the ring gears in a direction parallel with rotation axes of the ring gears.