An image pickup apparatus includes an imaging optical system; a display unit; a detecting unit performing focus detection in phase difference detection; a focusing unit performing focus control of a lens in the imaging optical system on the basis of the focus detection result; an imaging unit generating an image signal concerning an optical image of a subject; an electronic zoom unit zooming in or out the image of the subject displayed in the display unit on the basis of the image signal by performing signal processing; and a switching unit switching between an electronic zoom active state and an electronic zoom inactive state. The detecting unit includes a sensor unit including a first licensor and a second licensor; a setting unit that sets detection sections having the same section length in the first and second licensors; a focus detecting unit; and a section length controlling unit.