A queue selection method for controlling selection of many queues without increasing the circuit scale is provided. Queues are organized into groups, and each group is created as a tree structure with a plurality of steps, and a queue is selected by selecting a group of each step. By this, even if the number of queues is enormous, it is sufficient to provide registers for managing the presence of packets only for the number of groups selected in each step, and it becomes unnecessary to provide registers for all of the queues, so an increase of registers can be suppressed even if the number of queues increases. It is preferable that group selection in each step is performed in parallel independently from pipeline processing so as to maintain high-speed operation.