An imaging apparatus and an image processing method capable of increasing correction accuracy of a phase difference detection pixel even in a case where the phase difference detection pixel is densely arranged in an imaging element in order to secure AF performance are provided. An imaging element includes normal pixels of RGB and first and second phase difference pixels of which opening portions are adjacently arranged to face each other in a horizontal direction and in which a G filter is arranged. A pixel value addition unit (64) generates an addition pixel corresponding to a virtual G pixel at a pixel position between the first and second phase difference pixels by adding pixel values of the pair of the first and second phase difference pixels. In a case where the first or second phase difference pixel is set as an in-focus pixel that is an interpolation target, an average value interpolation unit (62) uses the normal pixels surrounding a pixel position of the in-focus pixel and the addition pixel in a case of performing an interpolation operation on a pixel value at the pixel position of the in-focus pixel.