PURPOSE: To execute auto-focusing of a high quality by a simple operating circuit, by controlling the driving end of a lens by addition and subtraction of a signal showing the defocusing extent by focal detection of a TTL type, and a signal related to movement of the lens.

CONSTITUTION: When a lens 1 is moved in the direction as indicated with an arrow 3 along an optical axis 0 so that it forms an image correctly on its prearranged image-forming surface 2, a pulse signal related to movement of the lens 1 is applied to a driving control unit 14 from a driving indicating unit 13. Also, on positions 4, 5 and 6 corresponding to the prearranged image-forming surface 2 and positions before and behind its surface, a sensor for detecting a focus is provided, respectively, and a signal showing the defocusing extent and direction from these sensors is applied to the driving control unit 14 from the driving indicating unit 13. The driving control unit 14 adds and subtracts a signal showing the inputted defocusing extent and a signal related to movement of the lens, by an operating circuit part, and controls the driving end of the lens 1.