An ignition coil for an internal-combustion engine, including an assembly of a primary coil, a secondary coil, and a central core, and a ring-shaped outer core surrounding the assembly. The assembly includes at least one first protrusion protruding from a first end surface of the secondary spool. The at least one first protrusion is in contact with an inside surface of the outer core and offset from the central core toward an opening of the outer core in a penetration direction of the outer core. The assembly further includes at least one second protrusion protruding from a second end surface of the primary spool. The at least one second protrusion protrudes beyond a second axial end surface of the central core so as to be in contact with the inside surface of the outer core and extends substantially the entire length of the outer core in the penetration direction.