PURPOSE: To enable automatic focusing up to a practical distance with reflected light by auxiliary light even in the case that a phase difference cannot be detected.

CONSTITUTION: Light incident on a lens 1 is transmitted through a stop 2 and a 45-degree mirror 3, and then, it is reflected on a submirror 4 positioned behind the mirror 3. And, the light is transmitted through a lens 10 in an AF optical system so as to be made incident on an AF sensor 11. When the brightness of an object is low and the contrast of the object is low, the auxiliary light is emitted in the case that the auxiliary light and a stroboscope are incorporated with the camera, meanwhile, in the case that the stroboscope is not incorporated with the camera, a warning that the stroboscope must be loaded is given by a sounding part 13, and then, the auxiliary light incorporated with the stroboscope is emitted. When an image spacing is not obtained even in the case of emitting the auxiliary light, first of all, it is judged that a defocusing quantity is large, then, a focal position is searched within an extent capable of moving a lens, and when the focal position is not detected, it is judged that the object is in the distance, so that the storobe light is emitted instead of the auxiliary light.