While normal pain perception is necessary for increasing survival possibility of organisms, chronic pain is a great source of disability and is a serious social problem. On pain perception, dorsal root ganglion (DRG) neurons generate electrical activity by nociceptive stimuli, and transmit signals toward spinal cord. Alteration in pain processing circuit of spinal cord network can cause a type of chronic pain called nociplastic pain. Conventional studies using model animals are limited to investigate the complex mechanisms of functional changes in neural networks. In this study, we aimed to reconstruct the sensory-spinal cord network in vitro in order to investigate functional changes in spinal cord networks by sensory inputs. A microdevice was fabricated for co-culturing DRG and spinal cord neurons on a chip. Electrical activity was induced with optogenetic stimulation toward DRG neurons, and extracellular potentials of spinal cord neurons were recorded with high-density microelectrode arrays. Spinal cord neurons showed network-wide bursting before the stimulation. The network burst become more frequent during stimulation of DRG neurons, and interestingly the change had been maintained for at least 20 min after stimulation. The result showed that synaptic inputs from DRG neurons enhance the activity of spinal cord neurons. Overall, our reconstructed network is feasible for studying functional changes in spinal cord network by sensory inputs.