PURPOSE: To suppress a the quantity of vapor fuel generated inside a fuel tank so as to miniaturize a canister.

CONSTITUTION: A shutter valve 4 opened at the time of inserting an oil supply gun and an elastic seal member 5 sealed along the outer circumferential part of the oil supply gun are provide in the fuel tube 2 of a fuel tank 1. A canister 9 is communicated via a charge passage 6 with the upstream of the shutter 4, Which is downstream side of the elastic seal member 5 of the fuel tube 2. A one-way 10 in which valve opening pressure is comparatively high is arranged on the way of the charge passage 6, and the oneway valve 10 is opened when fuel tank inner pressure is higher than the atmospheric pressure by about 7.3 kilophascal (55mmHg) at the time of fuel supply.