An optical element device includes an opto-electric hybrid board sequentially including an optical waveguide having a mirror, and an electric circuit board having a terminal in a thickness direction, and an optical element optically connected to the mirror and electrically connected to the terminal. The opto-electric hybrid board includes a mounting region including the mirror and the terminal when projected in the thickness direction and mounted with the optical element. Furthermore, the opto-electric hybrid board includes an alignment mark for aligning the optical element with respect to the mirror. The alignment mark is made of a material for forming the optical waveguide, and disposed at both outer sides of the mounting region in a width direction.