Provided is an ignition coil device for an internal combustion engine, including: an insulating case; an ignition coil device main body accommodated inside the insulating case, the ignition coil device main body including: a coil assembly; a center core arranged on an inner side of the coil assembly along a center axis of the coil assembly; a side core arranged on an outer side of the center core and the coil assembly; and an elastic cover provided to the side core; an igniter, which is accommodated inside the insulating case; and a filler, which is provided so as to fill the insulating case and is hardened, wherein the elastic cover includes: a covering portion configured to cover the side core; and a protruding portion, which protrudes from the covering portion, and is configured to relax a stress generated in the filler.