An all solid state battery includes a battery body including first and second surfaces opposing each other in a first direction of the battery body, third and fourth surfaces opposing each other in a second direction of the battery body, and fifth and sixth surfaces opposing each other in a third direction of the battery body, a solid electrolyte layer, and a cathode layer and an anode layer stacked in the third direction with the solid electrolyte layer therebetween, a cathode penetration electrode, and an anode penetration electrode opposing the cathode penetration electrode in the second direction; a cathode terminal; and an anode terminal. An average margin of the cathode layer from an edge of the cathode layer to the third surface in the second direction is within a range of 15% or more and 30% or less of an average width of the battery body in the second direction.