An imaging device includes an imaging sensor, a switching section, and a controlling section. The imaging sensor includes a light receiving surface to which light receiving elements capable of addressing reading are arranged, and having, on the light receiving surface, an imaging area capturing a subject image and an optical black area outputting a signal of a dark current component, the optical black area which the light receiving elements are covered with a light shielding member. The switching section switching a first state and a second state. The controlling section reads a signal level by each partial area at the optical black area when a dark image is captured in the second state after capturing a normal image in the first state, sequentially compares with the signal level at a corresponding position of the normal image, and controls a exposure time of the dark image according to the comparison result.