1. An associative information storage device comprising: an associative information storage circuit, including at least one neural network, for obtaining a state output from a state input by inputting associative matrices from a source exterior to said circuit and conversion means to obtain said state input for a succeeding time period by converting said state output using a nonlinear conversion; initial value input means for inputting a fixed initial state to said associative information storage circuit; storage means for storing progression of state transitions of said associative information storage circuit; and associative matrix processing means for generating associative matrices of said neural network based on an input pattern.