The layered superconducting material is characterized by a crystal structure in which a SnAs layer (wherein Sn and As are two-dimensionally bonded to develop superconductivity) and a Na layer (the spacer layer) are alternately laminated. Considering that such a layered structure is similar to that of a cuprate- or iron-based high-temperature (high-Tc) superconductor, it is possible that in SnAs-based layered materials, superconductivity is developed as a result of the unconventional pairing mechanism.