When the size of a macroblock for video image encoding is increased and decreased, the amount of information for describing the size information of the macroblock increases, resulting in a decline in the compression ratio. An image encoding device of the present invention is provided with a CU division unit and a CU size storage unit. The CU size storage unit stores size information for encoded CUs in a stored picture to be encoded, and size information for all CUs in previous and subsequent pictures used for prediction. The CU division unit uses the CU size information stored in the CU size storage unit to predict the CU size at a location to be encoded, and determines the CU size of a final CU to be encoded.
