1. An image pickup apparatus comprising: an image sensor configured to capture an image of an object formed by an imaging optical system; a focus detection area setting unit configured to set a focus detection area with respect to a face detection area of the object within an imaging plane of the image sensor; and a focus detection unit configured to obtain a focus evaluation value indicating contrast in a focus evaluation direction of the object in the focus detection area set within the imaging plane of the image sensor based on an image signal obtained by photoelectric conversion by the image sensor, wherein the focus detection area setting unit sets the focus detection area such that a length of the focus detection area in the focus evaluation direction is shorter than a length of the focus detection area in a second direction perpendicular to the focus evaluation direction regardless of a tilt of a face of the object.