1. A motion estimator of a video encoder, comprising: a search region data memory for storing video data of a previous video frame; a macroblock data memory for storing macroblock data of a current video frame; a first sub sampling circuit for sub-sampling by ratio M: 1 the video data of a previous frame read from the search region data memory in response to a sub-sampling rate control signal; a data array circuit for arraying video data outputted from the first sub-sampling circuit so that motion vector estimation candidates can be outputted sequentially a second sub-sampling circuit for sub-sampling, by ratio M: 1, current video frame data read from the macroblock data memory in response to the sub-sampling rate control signal; a search region deciding circuit for outputting a search region decision signal; a processing element (PE) array network for sequentially calculating a SAD (sum of absolute differences) value of the data outputted from the first sub-sampling circuit and the search region data outputted from the data array circuit, according to a designation of the search region decided by the search region deciding circuit, to sequentially output a plurality of SAD values; a motion vector comparator for receiving the plurality of SAD (sum of the absolute differences) values sequentially outputted from the PE array network, and comparing the SAD value with a previous SAD value, to detect a minimum SAD value as a motion vector value.