PURPOSE: To provide a device for updating coupling coefficient for pulse density type signal processing circuit network with which learning processing with an arbitrary learning coefficient is enabled in a pulse density type neural network.

CONSTITUTION: This device is provided with a storage means (η-Mem) 51 for holding a learning coefficient value η, random number generator (Ran-Gen) 50 for generating a random number value, comparator (CMP) 52 for generating a learning coefficient pulse having the learning coefficient value as pulse density by comparing the learning coefficient value with the random number value, and AND circuit 53 for ANDing the learning coefficient pulse and the error signal pulse sequence of a neuron.