A display device (1) includes: a light source (101) that outputs a laser beam; an illumination optical system (102) that emits illumination light of the laser beam; a diffraction pattern generation unit that generates a diffraction pattern from original image data; a spatial modulation element (103) that diffracts the illumination light by displaying the diffraction pattern; and a display control unit that performs at least one of a change in a display timing of a diffraction pattern the spatial modulation element (103) displays and a change in a size of a diffraction pattern the diffraction pattern generation unit generates.