To allow arithmetic processing using a plurality of processing nodes to be executed with a smaller memory size, an arithmetic processing apparatus for executing processing using a hierarchical type network formed by the plurality of processing nodes, comprises: a storage unit configured to store a parameter used by each of the plurality of processing nodes for arithmetic processing and a calculation result of the arithmetic processing in each of the plurality of processing nodes; and a buffer control unit configured to switch, based on a configuration of the hierarchical type network, a buffer system of the parameter and the calculation result in the storage unit in at least one layer of the hierarchical type network.