Holographic display device and method for generating hologram

A holographic display device and a method for generating a hologram are disclosed. The holographic display device generating a hologram includes a storage unit (180) and a control unit (190). Herein, the storage unit stores at least one look-up table each storing a partial size (400, 600) of a full size (300,500) sub-hologram for reconstructing object point (OP), wherein the object points (OP) are included in a scene reconstructed by the generated hologram. And, the control unit uses at least one look-up table each having the partial size, so as to calculate hologram values for the sub-holograms for reconstructing object points (OP), wherein the object points (OP) are included in the scene, and then the control unit generates the hologram by overlapping the hologram values of the sub-holograms.