An autofocus system for a camera includes a contrast focus detector which detects a position of a focusing lens group, at which the contrast of an object image reaches a maximum as a contrast in-focus position; a phase-difference focus detector which separates the object image light bundle into two light bundles which form two object images on a light-receiving element to detect a phase difference between the two object images formed thereon, the phase-difference focus detector defining a position of the focusing lens group at which an in-focus state is obtained for the object as a phase-difference in-focus position; and a controller for moving the focusing lens group via the lens driver to the phase-difference in-focus position or the contrast in-focus position. The controller adjusts a moving range of the focusing lens group in accordance with a degree of reliability of the phase-difference in-focus position.