A light emitting device includes a first light-emitting-element row that includes light emitting elements arranged in a row in a main scanning direction and a second light-emitting-element row that includes light emitting elements arranged in a row in the main scanning direction and that is positioned in such a manner that at least a portion of the second light-emitting-element row overlaps the first light-emitting-element row in a sub scanning direction. The first and second light-emitting-element rows are each formed by arranging light-emitting-element array chips in each of which the light emitting elements are arranged in a row in the main scanning direction. In each of the light-emitting-element array chips, a pitch of the light emitting elements arranged in a row is changed from a first pitch to a second pitch, which is different from the first pitch, in a central region of the row of the light emitting elements.