A clip for mounting a first member on a second member includes a first placement portion adapted to be placed in the first member; a second placement portion adapted to be placed in the second member; and a flange portion provided between the first placement portion and the second placement portion. The second placement portion includes side walls on two sides, each having an elastic engagement piece formed by a notch, and a shielding wall provided between the side walls and shielding a space between the side walls from an upper side. An engagement end portion of each of the elastic engagement pieces extends to a first placement portion side.