An all-solid battery having a high output power, exhibiting high safety, and capable of being produced at a low cost is provided. The all-solid battery (8) includes an internal electrode body (6) having a cathode (1) comprising a cathode material, an anode (2) comprising an anode material, and a solid electrolyte layer (3) comprising a solid electrolyte, the cathode material, the anode material, and the solid electrolyte being phosphoric acid compounds, the internal electrode body (6) being integrated by firing the cathode (1), anode (2), and solid electrolyte layer (3), and the internal electrode body (6) containing water.