An imaging device that is able to display an image with an aperture value at the time when actually photographing on a liquid crystal display monitor for displaying an image, in a single-lens reflex digital camera is provided. In a depth-of-field preview mode, a quick return mirror (4) is retracted from an optical path and light is incident on an imaging sensor (11). Then, an imaging optical system is controlled to be in an actual aperture state, and by displaying an image data obtained at the imaging sensor (11) on the liquid crystal display monitor (16) for displaying an image, a plurality of images with aperture values at the time of actually photographing, in other words, actual aperture live view images, can be concurrently displayed simultaneously on the liquid crystal display monitor (16) for displaying an image. By doing so, it is possible to easily compare images with different depths of field, and it is possible to simultaneously photograph images with different depths of field.