IGNITION COIL

Provided is an ignition coil which is capable of maintaining reliable insulation performance over a long period of time. A coil main body unit (BDY), which houses a primary coil (L1) and a secondary coil (L2) as well as a switching element (Q), is configured such that the coil main body unit is segmented into a case main body (10) in which a housing space is provided, and a case lower portion (20) which abuts the perimeter of the case main body, and the primary coil and the secondary coil, which are placed in the case lower portion (20), are covered by the case main body (10). The secondary coil (L2) is configured by winding a second winding (41) around a secondary bobbin (40), through which a central hole (H2) is extended in the horizontal direction, and the outer periphery of the same is covered by the case lower portion (20) and a protective cap (42) and filled with a first material. In a state in which the primary coil (L1) is placed in the central hole (H2), the remaining gap is filled with a secondary material.