An optical writing device includes: a light emitting substrate on which light emitting device groups obtained by grouping light emitting devices is arranged; a lens array including image forming lenses condensing light emitted from the light emitting devices on an image carrier; a first base material including the lens array; and a second base material including the light emitting substrate or the lens array, wherein the first and/or second base materials, each of which includes a joint formed in a joint part with the other member, is a transparent body, the joint includes a metal layer, an intermediate layer providing a peak of total transmissivity of the joint in a first wavelength band, and a marker for alignment, the first and second base materials are joined via the metal layer, and the light emitting devices emit light of a wavelength band out of the first wavelength band.