Abstract: A rubber plug has a tubular sealing function portion that allows an electric wire to pass through the tubular sealing function portion and a tubular low-rigidity portion that allows the electric wire to pass through the low-rigidity portion. The sealing function portion exhibits sealing performance by elastically coming into close contact with the inner peripheral surface of the terminal accommodating chamber and the outer peripheral surface of the electric wire. The low-rigidity portion has a lower rigidity than the sealing function portion, and is arranged rearward of the sealing function portion.

Abstract: A rubber plug has a tubular sealing function portion that allows an electric wire to pass through the tubular sealing function portion and a tubular low-rigidity portion that allows the electric wire to pass through the low-rigidity portion. The sealing function portion exhibits sealing performance by elastically coming into close contact with the inner peripheral surface of the terminal accommodating chamber and the outer peripheral surface of the electric wire. The low-rigidity portion has a lower rigidity than the sealing function portion, and is arranged rearward of the sealing function portion.

Abstract: Provided is an internal combustion engine of a vehicle. An upper surface of a head cover supporting plug top coils is covered with an engine cover. A plug top coil cover is fixed to the upper surface of the head cover. Thereby, an upper passage is formed between the engine cover and the plug top coil cover, and a lower passage is formed between the head cover and the plug top coil cover. The lower passage includes a labyrinth defined by first wall parts provided for the head cover and second wall parts provided for the plug top coil cover. Since it becomes difficult for high-temperature air to flow along the lower passage facing the plug top coils, and easy for it to flow along the upper passage away from the plug top coils, the overheating of the plug top coils caused by contact with the high-temperature air is suppressed.