Provided is a method that is for attaching a filler pipe. The method for attaching a filler pipe attaches a filler pipe to the aperture of a fuel tank with an attachment member therebetween, and is characterized by containing: a fitting step for fitting the tubular attachment member to the inside of the aperture of the filler pipe; a contact step for contacting, to the surface at the periphery of the aperture of the fuel tank, a first flange protruding outwards in the radial direction from the outer peripheral surface of the attachment member, and a second flange protruding outwards in the radial direction from the outer peripheral surface of the filler pipe; and a welding step for welding the first flange and second flange to the surface.