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DC‐powered Josephson logic gates have the advan tage of being free from operation error due to crosstalk from power current in contrast to ordinary ac‐powered Josephson logic gates. One of these, the HUFFLE (hybrid unlatching flip‐flop logic element) gate using stacked Josephson interferometers (JI) can execute complicated logic functions by itself. Therefore, high‐Speed operation of logic circuits using HUFFLE gates may be expected because the number of logic stages in the circuits is reduced. to investigate the improvement in circuit per formance by using HUFFLE gates with the stacked structure, the authors have fabricated a 6‐bit arithmetic logic unit (ALU) and tested its operation. Two new logic gales, exclusive OR and majority, newly developed using the stacked structure have been developed. the ALU which performs the four functions, AND, OR, exclusive OR, and ADD, is realized with seven logic stages. Ac cordingly, reduction in the number of logic stages and execution time of the ALU by use of the stacked HUF FLE gate family is confirmed.