An apparatus for, by inputting data to a hierarchical neural network and performing operation processing in each layer of the network, calculating a feature plane in the layer, comprises an operation unit, a feature plane holding unit including at least one memory that holds a feature plane to be processed, a unit configured to control to arrange the feature plane in the memory based on network information as information about each layer undergoing the operation processing and to manage reading/writing from/in the memory, and a processor configured to access, via a bus, the feature plane holding unit which is address-mapped in a memory space. The processor calculates, based on the network information, an address address-mapped in the memory space, reads out the feature plane, and processes the feature plane.