1. An image capturing apparatus comprising: an image sensor; a first detection unit that, based on feature amounts of an image obtained by the image sensor, detects a position of a certain subject in the image and a position of a certain part of the certain subject; a second detection unit that detects a position of a region of the certain subject in the image obtained by the image sensor with a smaller calculation amount than the first detection unit; a selection unit that selects, from among a plurality of focus detection areas, a focus detection area to be focused on; and an autofocus unit that performs autofocus on the selected focus detection area, wherein the selection unit selects a focus detection area corresponding to the certain part based on a relationship between the position of the region of the certain subject detected by the second detection unit and the positions of the certain subject and the certain part detected by the first detection unit.