An apparatus that calculates a Sum of Absolute Differences (SAD) for motion estimation of a variable block capable of parallelly calculating SAD values with respect to multiple current frame macroblocks at a time is presented. The apparatus includes a PE array unit including at least one Processing Element (PE) that is aligned in the form of a matrix, and parallelly calculating a SAD value of at least one pixel provided in multiple serial current frame macroblocks, a local memory including current frame macroblock data, reference frame macroblock data, and reference frame search area data, and transmitting the data to each PE that is provided in the PE array unit, and a controller for making a command for the data that are provided in the local memory to be transmitted corresponding to at least one pixel, on which each PE provided in the PE array unit performs calculation.