Provided is an apparatus and method for encoding a hologram and evaluating a holographic image quality for an amplitude-modulated hologram. A hologram encoding method may include acquiring three-dimensional (3D) information of a scene or an object; generating hologram information based on the 3D information; deriving a real number hologram function by extracting a real number part and an imaginary number part from the hologram information; determining an intermediate hologram function based on a sign characteristic of the real number hologram function; and determining encoded hologram information based on the intermediate hologram function.