Imaging device and focusing control method for same

In the present invention, a phase-difference AF processing unit of a digital camera provided with an imaging element including a pair of phase-difference detection pixels for capturing an image of a subject through a lens device including an APD filter calculates a parameter relating to the ratio of the phase difference between detection signals detected by each of the phase difference detection pixels and a defocus amount on the basis of the incidence angle range of light incident on the pair of phase-difference detection pixels through the lens device, the transmittance in a region of the APD filter through which light in the incidence angle range passes, and the light sensitivity distribution of light sensitivity for each incidence angle of light on each of the phase-difference detection pixels, and calculates a defocus amount using the parameter and the phase difference.