Abstract: The present invention relates to an output buffer type Asynchronous Transfer Mode(ATM) switch that enables decentralized processing, which simultaneously sends multiple inputted cells to each output line, and makes implementation easy by modularization, and without speed-up, could process high-speed data inputted/outputted through input/output lines by comprising: a Batcher Sorting Network arraying, in the order of output line group number, N(N=2.sup.1, 2.sup.2, . . . , 2.sup.n, n is natural numbers) cells simultaneously inputted through N input lines of the switch; an Expanded Banyan Routing Network outputting cells arrayed in said Batcher sorting Network to the corresponding output line group containing each output line; and an Output Queueing Modules temporarily storing cells, outputted from said Expanded Banyan Routing Network, in the buffer used as a common memory and sending these cells to the final output lines.