The present disclosure relates to a novel neuron circuit using a p-n-p-n diode to realize small size and low power consumption. The neuron circuit according to one embodiment of the present disclosure may generate potential by charging current input from synapses through a capacitor. In this case, when the generated potential exceeds a critical value, the neuron circuit may generate and output a spike voltage corresponding to the generated potential using a p-n-p-n diode connected to the capacitor.