PURPOSE: To miniaturize a motion vector detector.

CONSTITUTION: For instance, cascade connected PEs 110-140 respectively calculate partial similarity degrees between a present image block and a reference image block from present image data DT and reference image data DA or DB, and the respective PEs 120-140 add the calculated results in the preceding stage. The output data width of the PE 140 becomes 8+Log2M when the size of picture data 8 bits and the block is defined as M×M picture elements. The output data of the PE 140 are tentatively held in a RAM 204 and an adder 201 uses the held data of the RAM 204, cumulatively adds the output of the PE 140, obtains an error amount between both blocks and transmits it to a comparison part 210. The side of the respective PEs 150-180 performs operations by using the reference picture data DB or DC as well and the adder 202 transmits the error amount to the comparison part 210. The comparison part 210 obtains a vector for minimizing the error amount and outputs it as a motion vector.