Ignition coil and ignition device

An ignition coil for use in an internal combustion engine, comprising:

• a first primary coil including a first primary winding, in which a direct-current voltage is applied to one end and the other end is connected to a ground point;
• a first secondary coil including a first secondary winding;
• a first penetrating core that penetrates an inside of the first primary coil and an inside of the first secondary coil and is configured to electromagnetically couple the first primary coil and the first secondary coil;
• a second primary coil including a second primary winding, in which the direct-current voltage is applied to one end and the other end is connected to the ground point;
• a second secondary coil including a second secondary winding;
• a second penetrating core that penetrates an inside of the second primary coil and an inside of the second secondary coil and is configured to electromagnetically couple the second primary coil and the second secondary coil;
• a one-end peripheral core connecting one end of the first penetrating core and one end of the second penetrating core;
• an other-end peripheral core connecting the other end of the first penetrating core and the other end of the second penetrating core;
• and a casing that is opened upward to have a concave shape in which an opening is formed at an upper end, and accommodates the first primary coil, the first secondary coil, the first penetrating core, the second primary coil, the second secondary coil, the second penetrating core, the one-end peripheral core, and the other-end peripheral core, wherein the casing is filled with thermosetting mold resin, and respective upper ends of the one-end peripheral core and the other-end peripheral core are positioned above the first secondary coil and the second secondary coil.