An optical apparatus includes a first driver configured to drive a focus lens unit in autofocusing, a second driver configured to drive the focus lens unit in the autofocusing, a first detector configured to detect a driving amount of the first driver, a second detector configured to detect a driving amount of the second driver, a memory configured to store a relationship between information of detection results of the first and second detectors, and an object distance as a distance from the optical apparatus to an object, and a controller configured to obtain information of the object distance based upon the relationship stored in the memory and the detection results of the first and second detectors.