An ignition coil for an internal combustion engine according to the present embodiment includes a primary coil, a secondary coil, a center core, an outer circumferential core, an igniter, a case, a connector unit, and a relay member. The relay member electrically connects the outer circumferential core and a grounding terminal member. The relay member includes: a base portion provided along the rear surface of an engagement wall; a standing portion standing rearward of the base portion; and a curved portion that extends from a rear end of the standing portion in a vertical direction Z orthogonal to a coil axis direction X and is curved to protrude rearward. The base portion is in contact with an inner grounding terminal at one end in the vertical direction Z. The standing portion is provided further outward than the igniter in a horizontal direction Y. The curved portion is elastically deformed and is urged against a front surface of the outer circumferential core.