An imaging device, comprising an image sensor having image pixels and phase difference pixels, a phase difference detection section that detects a phase difference based on pixel data of the phase difference pixels, a pixel data calculation section that calculates pixel data of virtual imaging pixels at positions of the phase difference pixels, a degree of coincidence calculation section that calculates a degree of coincidence between each pixel data of the virtual imaging pixels that has been calculated, a reliability determination section that determines reliability of the phase difference detection result in accordance with the degree of coincidence, and a focus adjustment section that performs focus adjustment based on the phase difference detection result and the reliability.