GAS TANK

Provided is a gas tank such that the pressure of gas filled inside does not tend to rise. A hydrogen gas tank (1) is equipped with a container body (10) filled with hydrogen; a first thermally foamed heat insulation layer (21) which is provided to the outer surface (11) of the container body (10); a belt installation region (16) which is virtually provided to part of the outer surface (11) of the container body (10); a belt (31) such that a back surface (35) which is part of the surfaces of the belt (31) is in contact with the belt installation region (16) and is fixed to a vehicle body (141), resulting in the container body (10) being fixed to the vehicle body (141); and a second thermally foamed heat insulation layer (41) that is provided to that surface of the belt (31) which is other than the back surface (35).