An ignition coil device for an internal combustion engine, which has a superior waterproof property and can be reduced in size and easily produced. An annular seal rubber (2) is mounted to the lower side of an ignition coil device (1). An annular projection (2a) is provided on a part of the seal rubber and is pressed against the inner diameter surface of a plug hole. A substantially L-shaped groove for forming an air path (4) is formed in a part of a coil case (1a). The air path (4) is formed by mounting the seal rubber (2) into the groove, enabling the inside and the outside of the plug hole to communicate with each other. A thin film resin member (3) with a porous structure being permeable to gas but not to liquid is fixedly bonded to an inlet (4a) of the air path (4) to prevent water from entering the plug hole. Those features realize the ignition coil device for the internal combustion engine, which has a superior waterproof property and can be reduced in size and easily produced.