A cylindrical joining member is fitted into a member to be joined that is made of a material different from the joining member. Plastic deformation is effected in a soft material of the member to be joined to hermetically join the two members together. Joining faces are provided to the two members that face and are joined to each other by the plastic deformation and with an elastic deformation pressure in an axial direction. The soft material of the member to be joined, which is located in a circumferential direction of the member, bites into a joining portion of the joining member by the plastic deformation and with the elastic deformation pressure.