To provide a coupling coefficient updating method faithfully leading out learning algorithm from a neuron output function and realizing learning processing through the use of a simple logical circuit.

The plus component of a differential signal δk+ (or an inversion signal by an inverter 45) at a neuron (k), the minus component δk- of the same signal (or an inversion signal by an inverter 44 and S'kj are inputted in an AND circuit 46 or 47 and processed by η circuits 38 and 38. Then the signal obtained by the processing is set to be the plus component Δkj+ of the updated quantity of the coupling coefficient or the minus component Δkj- of the updated quantity of the coupling coefficient. When the OR output of the Δkj+ and a coupling coefficient pulse Wkj before update by means of an OR circuit 48 is '1', '1' is added at an up/down counter 41 and when the kj is '1', '1' is subtracted at the up/down counter 41 to set the result value obtained by these adding and subtracting processing to be a new coupling coefficient.