[Problem to be Solved] A gas fuel vehicle capable of detecting a gas leakage on the back side of a fuel fill port (inside of a vehicle body) extremely easily is provided.[Means for Solving the Problem] The gas fuel vehicle includes: a gas filling port that receives a supply of a gas fuel from a fuel supply device on the outside of a vehicle body; a communicating hole that connects the inside of the vehicle body and the outside of the vehicle body; a shielding member that shields the fuel fill port and the communicating hole from the outside of the vehicle body; and a gas fuel storage unit that stores the gas fuel supplied from the fuel supply device through the fuel fill port. A rod portion of a gas leakage detector is inserted into the communicating hole from the outside of the vehicle body, thereby detecting a gas leakage inside the vehicle body.