An automatic focusing system for a camera includes a light emitter for emitting a distance measuring light beam and a condenser lens for condensing the light beam reflected by an object. A light spot detector produces output signals corresponding to the position of the focused spot of reflected light impinging thereon. Various circuitry, including adders and subtracters and amplifiers and rectifiers and integrators are provided for processing the output signals of the light spot detector. A lens encoder detects the existing focusing position of a picture taking lens and further circuitry is provided for comparing the existing focusing position of the picture taking lens with a desired optimum focusing position and for driving the lens by a lens driving unit so as to move the lens to its optimum focusing position.