This invention constitutes a measuring distance device including a sensor array which detects image signals of an object in a finder screen, a projection unit which projects a signal light on the object, a selection unit which selects a detection area for the image signal of the sensor array, a change unit (control unit) which makes detection areas selected by the selection unit different from each other when the signal light is projected or is not projected by the projection unit, and a focus adjustment unit which performs focus adjustment by an image signal output in the detection area of the sensor array selected by the selection unit. A reduction in time lag is achieved without increasing a read area, and an influence of harmful light is reduced. This device which can perform an accurate and high-speed process can be applied to a hybrid AF camera.