An optical modulation element is capable of forming a reflective diffraction grating in which heights of a plurality of elements each having a reflecting surface periodically change. The reflecting surfaces of at least one of the plurality of elements are driven in a direction of height by piezoelectric elements. The plurality of elements each having the surface as the reflecting surface are two-dimensionally arrayed by juxtaposing long sides. A rear surface side of an effective reflecting portion of each of the elements is fixed to the piezoelectric element.