1. An optical apparatus comprising: a first focus detector which detects a focus state on a subject; a second focus detector which detects a focus state on the subject in a detection method different from a detection method of the first focus detector; and a controller which has a function of detecting whether or not the subject is a moving body and a function of performing focus control of an image-taking optical system in a first sequence in which at least one of the first and second focus detectors is used and a second sequence in which at least the other of the focus detectors is used, wherein the controller preferentially uses one of the first and second sequences depending on the result of the detection with the moving body detecting function.