An optical element according to an embodiment includes: a lens array including a plurality of convex shaped lenses provided on a first surface thereof and taking a flat shape at a second surface which is opposite from the first surface; a lens holder comprising concave portions formed to correspond to respective lenses in the lens array, at a surface opposed to the lens array, each of the concave portions having a size which makes it possible for one of the convex shaped lenses corresponding to the concave portion to fit therein; and a drive unit configured to drive at least one of the lens array and the lens holder to bring the convex shaped lenses in the lens array and the concave portions in the lens holder into an isolation state or a contact state.