A fuel cut-off valve 100 of the invention is attached to an upper portion of a fuel tank and connects and disconnects inside with and from outside of the fuel tank according to the fuel level in the fuel tank. In the fuel cut-off valve 100 of the invention, a valve casing 110 forms a first valve chest 120 and a second valve chest 130 connected to the fuel tank and has an inter-valve chest flow passage 112 connecting the first valve chest 120 to the second valve chest 130 and a canister connection port 102 connecting the second valve chest 120 to a canister placed outside the fuel tank. A first float 124 and a second float 134 are respectively located in the first valve chest 120 and in the second valve chest 130. When the fuel level in the fuel tank rises to reach a preset first level FL1, the first float 124 moves up to close an opening 122 and thereby close the inter-valve chest flow passage 112. When the fuel level in the fuel tank further rises to reach a preset second level FL2 that is higher than the preset first level FL1, the second float 134 moves up to close an upstream end opening 132 of the canister connection port 102 and cut off the flow of fuel vapor to the canister. This arrangement of the invention effectively ensures the sufficient performances and the enhanced reliabilities of the leakage protection function and the backflow prevention function of the fuel cut-off valve.