Provided are a digital hologram synthesis method and apparatus based on an angular spectrum. The digital hologram synthesis method includes representing an input digital hologram as at least one angular spectrum region by applying Fourier transformation to the input digital hologram, registering the at least one angular spectrum region by projecting the at least one angular spectrum region onto a spherical surface, and generating a synthesis digital hologram based on the registered at least one angular spectrum region. Accordingly, it is possible to generate a new digital hologram with a different orientation or at a different distance using an angular spectrum of a digital hologram generated in advance, without geometric information of an object. In addition, it is possible to readily and intuitively synthesize a new digital hologram while viewing an image visualized in a 3D space.