An imaging apparatus is provided which comprises: an imaging unit 22 that captures an image through an optical system and outputs an image signal corresponding to the captured image; a focus detection unit 21 that uses the image signal as the basis to detect a focal state of the optical system at a plurality of focus detection positions set in an image plane of the optical system; a calculation unit 21 that calculates a limit value at a closing side of an aperture value of the optical system as a closing side limit value, the limit value corresponding to a focus detection position when the focus detection unit 21 performs focus detection; and a control unit 21 that, when the focus detection unit 21 performs focus detection, sets the aperture value of the optical system on the basis of the closing side limit value corresponding to the focus detection position for performing focus detection.