In this study, a sputtered Mg film was fabricated as an anode, a natural magnesium silicate mineral was used as electrolyte, and an all-solid-state Mg battery with a carbon black electrode was assembled; subsequently, the battery’s electrochemical characteristics and charge–discharge mechanism were evaluated. Because the abundant interlayer water in the magnesium silicate mineral structure allowed for cations channel to form, the battery exhibited considerable ionic conductivity at room temperature. The magnesium silicate mineral was fabricated as a flexible cloth membrane solid-state electrolyte to improve its adhesion to the electrode surface and, consequently, enhance battery performance. During high-voltage charging, a visible blocking layer structure was formed on the surface of the Mg electrode. The formation of the blocking layer considerably increased the interfacial resistance of the battery, which was detrimental to the insertion and extraction of the Mg ions on the electrode surface and reduced the capacity of the solid-state battery. Thus, the solid-state Mg battery exhibited acceptable capacity and stability and the potential for application in energy storage systems.