An imaging device includes an imaging element that receives a subject light flux from an imaging lens that forms a subject image, and converts the subject light flux to an electrical signal; and a control device that selects one of first imaging preparatory processing for executing imaging preparatory processing based upon an output signal from the imaging element and second imaging preparatory processing for executing imaging preparatory processing based upon an output signal from a light receiving element other than the imaging element in correspondence to an extent of decentering of the imaging lens.