A valve mounting structure includes a mounting portion, a valve, and a cushion. The valve includes a valve seat having a cylindrical joining portion that receives the mounting portion inserted thereto, or is inserted to the mounting portion. The cushion is arranged between the mounting portion and the joining portion, and fixed to each of the mounting portion and the joining portion. In a case where one of the mounting portion and the joining portion is a first portion and the other is a second portion, the first portion includes a peripheral wall and an opening portion without the peripheral wall formed therein. A fixing portion in which the second portion and the cushion are fixed to each other is at least partly arranged at a position adjacent to the opening portion along a radial direction of the mounting portion.