A projection device is provided with at least: a laser light source which emits laser light; a conversion unit which converts the laser light into parallel light; a phase-modulation-type spatial modulation element which phase-modulates the parallel light on the basis of a supplied projection image and delivers phase-modulated light; and a control unit. The control unit includes: a projection image storage unit in which at least one projection image group is stored; a processing unit which, with respect to one projection image acquired from the projection image storage unit in synchronism with an update period, generates a combination of a plurality of diffraction patterns in the update period; and a projection image generation unit which supplies the combination of a plurality of diffraction patterns to the phase-modulation-type spatial modulation element as the supplied projection image.