Somatosensory information from the periphery is converted to an electrical signal, and transmitted to the spinal dorsal horn via primary afferent. In the spinal dorsal horn, the sensory information is appropriately processed by spinal neuronal circuits, and then relayed to the brain. Growing evidence shows that spinal astrocytes, which are known as a type of glial cells in the central nervous system, are activated by peripheral nerve injury and tissue inflammation and contribute to chronic pain and itch by modulating neuronal activity. However, their roles on somatosensory processing under physiological conditions remain unknown. Recently, we identified a population of astrocytes selectively located in the superficial layers of spinal dorsal horn in mice. Using in vivo imaging, genetic tools which selectively manipulate the function of a population of astrocytes and behavioral analysis, we found that the astrocyte population has a crucial role of mechanical hypersensitivity through descending locus coeruleus-noradrenergic pathway after peripheral noxious stimuli, which cannot be made by only neuronal circuits. These results define the novel role of spinal astrocytes in modulating mechanosensory behavior.