in fig3 the fuel filler port closing apparatus of the present example is configured by the filler neck 1 the closure unit 2 and the cover unit 4 the closure unit 2 is attached with the flapper 3 that is pushed down by the gasoline filling nozzle 71 see fig5 and 6 inserted from the opening 44 of the filler neck of the cover unit 4 to thereby open the opening 211 of the nozzle guide the cover unit 4 is pivotally attached with the upwardly rotatable cover 5 the cover 5 opens and closes the opening 44 of the filler neck the filler neck 1 is a tubular member integrally formed from one plate material through drawing process the shape of the filler neck 1 is such that the opening at the upper end is wide and a connection port 11 having the opening at the lower end is narrowed in accordance with an fuel filling tube main body 8 to be connected the closure unit 2 is a member made of synthetic resin the closure unit 2 is formed with a nozzle guide 21 for guiding the gasoline filling nozzle 71 see fig5 and 6 inserted from the opening 44 of the filler neck the flapper 3 that opens and closes the opening 211 of the nozzle guide is integrally assembled near the opening 211 of the nozzle guide the opening 211 localizes at the bottom of the nozzle guide 21 at the unit peripheral surface 22 an annular groove 221 is formed near the upper edge and a seal ring 222 is fitted.