PURPOSE: To obtain an inexpensive pattern identification device which processes the identification of an input picture by means of a neural network at high speed.

CONSTITUTION: A auto correlation pattern detecting device 1 operates the auto correlation of an input pattern and converts data of operation result into a neural network input data form. Here, the auto correlation operation of the input pattern is easily realized in the auto correlation pattern detecting device 1 by an operation circuit or a computer program. Thus, effective pattern identification is executed even on the small neural network scale by using data whose information quantity is excessively reduced as an input to the neural network 8. Since unnecessary information (that is, information which does not show a characteristic) is decreasing, the convergence of rapid learning is obtained.