An all solid battery includes: a solid electrolyte layer including phosphoric acid salt-based solid electrolyte; a first electrode that is formed on a first main face of the solid electrolyte layer; and a second electrode that is formed on a second main face of the solid electrolyte layer, wherein a D50% grain diameter of crystal grains of the phosphoric acid salt-based solid electrolyte is 0.5 μm or less, wherein a D90% grain diameter of the crystal grains is 3 μm or less.