Provided is an operation method for a digital hologram implementation device including a backlight and a spatial light modulator, the operation method including setting an initial phase value of an optical signal to a remedy phase, computing a reduced phase based on the remedy phase, correcting the remedy phase based on a difference between the reduced phase and a preset optimized phase, determining whether the corrected remedy phase is a stabilized phase, performing forward propagation on the stabilized phase and an amplitude of the optical signal, correcting the amplitude of the optical signal, performing backward propagation on the corrected amplitude and the stabilized phase, and determining whether a phase derived by the backward propagation is an optimized phase.