PURPOSE: To provide the synapse neural network expressing device of an analog storage system operating stably for many hours and subjected to high integration.

CONSTITUTION: A second neural network expressing unit 505 receives an output state of partial or all neurons of a first neural network expression unit, and decides whether a convergent state of this first neural network expressing unit is to be stored or not. A control circuit unit 550 corrects a synapse load value of a synapse expressing circuit contained in a first neural network expressing unit in accordance with an output signal of this second neural network expressing unit, and refreshes storage information of a first neural network expressing unit thereby. In such a way, the neural network expressing device which is refreshed in parallel in accordance with a state that the synapse load value is to be stored and can hold a stable synapse load value extending over many hours is obtained.