An exposing device including a light emitting element array of light emitting elements arrayed in a row along a predetermined first direction; a hologram recording layer in which hologram elements are multiplex recorded such that each of the hologram elements corresponds to one of the light emitting elements and diffracts an emission beam from the light emitting element and converges the light onto a light exposure plane, such that focused beam spots are formed on the light exposure plane in a row along the first direction; and a first transmission control section, disposed at the light incident side of the hologram recording layer, provided with a structure in which light blocking sections and light transmitting sections are alternately arrayed along a second direction intersecting with the first direction, and selectively transmitting in the second direction light passing along the optical path of the reference beam.