To reduce the cost of an ignition plug tube by making it of a cylindrical member and to provide a simple structure having only a small number of parts for mounting the ignition plug tube. A mounting structure of an ignition plug tube that is made of a cylindrical member includes a sealing member made of a soft member fitted to a cylinder head cover. The sealing member is interposed between the cylinder head cover and the ignition plug tube. The ignition plug tube is fixed and supported between an ignition plug plughole formed in a cylinder head of an internal combustion engine and the cylinder head cover.
