To provide a fuel cutoff valve 10 which realizes high sealing performance by preventing positional displacement when returning to an original position after a relief valve 70 is opened.

A fuel cutoff valve 10 contains a float mechanism 50 and pressure adjusting mechanism 60 in a casing 20. The pressure adjusting mechanism 60 includes: a float valve opening 74b provided facing a connection passage 74a and opened/closed by ascent/descent of the float mechanism 50; and a relief valve element 71 for opening/closing a relief valve opening 33b. The relief valve element 71 is a guide rib 33d formed facing a relief passage 33a and is guided in an axial direction near the relief passage 33a.