PURPOSE: To surely and quickly execute focusing even for a subject difficult to full automatically focus by using the semi-automatic focusing method for executing automatic focusing based on an instruction of a rough distance between a subject and a camera measured by a photographer's visual observation.

CONSTITUTION: To a known automatic focusing device, a photographing distance detecting means 3, a subject distance instructing means 4 and an arithmetic means 7 are added newly. By the distance detecting means 3, the moving--out quantity of a focus lens 2 is converted to a voltage d1 by a potentiometer method, and also, by a photographer's visual observation, a subject distance is instructed to the distance instructing means 4, and a voltage d2 is obtained by the potentiometer method. Subsequently, sharpness (s) of image formation of a photographing element 5 is detected by a sharpness detecting means 6, and based on d1, d2 and (s), a prescribed operation is executed by the arithmetic means 7, and corrected sharpness (s) is derived. Based on sharpness s2, a controller 8 moves a focal lens 2 by a prescribed quantity. In such a way, even in the case of a subject whose focusing is difficult by full automatic focusing, a sharp image of the subject can be obtained surely and quickly.