An image-pickup apparatus to which a lens unit that includes an image-pickup optical system including a focus lens is attachable includes an image sensor configured to photoelectrically convert an object image formed via the lens unit that has been attached, and to generate an image signal, and a controller configured to generate information on driving of the focus lens in the lens unit based upon the image signal and to provide focus control, the controller communicating data with the lens unit, wherein the controller transmits information on a driving target position of the focus lens to the lens unit in a first control, and transmits information on a driving direction and driving speed of the focus lens to the lens unit in a second control different from the first control.