A fuel apparatus includes a vapor passage for guiding evaporation gas in a fuel tank to a canister, a sealing valve for closing the vapor passage in normal condition to keep the interior of the fuel tank in a sealed state, a leak detection portion for detecting leak of the evaporation gas from the fuel tank in the sealed state to outside, and an opening control portion for opening the sealing valve when leak of the evaporation gas is detected. Alternatively, the fuel apparatus includes a bypass passage connecting an upstream portion of the vapor passage located upstream of the sealing valve and a downstream portion of the vapor passage located downstream of the sealing valve to each other to bypass the sealing valve, and a bypass valve provided in the bypass passage, for opening the bypass passage in the closed state when leak of the evaporation gas is detected.