A neural network system that can minimize circuit resources for constituting a self-learning mechanism and be reconfigured into network configurations suitable for various purposes includes a neural network engine that operates in a first and a second operation mode and performs an operation representing a characteristic determined by setting network configuration information and weight information with respect to the network configuration, and a von Neumann-type microprocessor that is connected to the neural network engine and performs a cooperative operation in accordance with the first or the second operation mode together with the neural network engine. The von Neumann-type microprocessor recalculates the weight information or remakes the configuration information as a cooperative operation according to the first operation mode, and sets or updates the configuration information or the weight information set in the neural network engine, as a cooperative operation according to the second operation mode.