An all-solid-state battery (1) includes a positive electrode (20) in which a first current collector layer (21) and a first active material layer (22) containing at least a solid electrolyte are laminated, a negative electrode (30) in which a second current collector layer (31) and a second active material layer (32) containing at least a solid electrolyte are laminated, and a first solid electrolyte layer (41) disposed between the first active material layer (22) and the second active material layer 32. In a direction perpendicular to a lamination direction, an area of the second active material layer (32) in the negative electrode (30) is larger than an area of the first active material layer (22) in the positive electrode (20), and in a direction perpendicular to the lamination direction, an area of the first solid electrolyte layer (41) is larger than an area of the first active material layer (22) in the positive electrode (20), and the porosity n1am of the first active material layer (22) is 5% or less.