There is provided a structural member configured to be disposed in an internal space of a fuel tank and support a wall of the fuel tank. The structural member has an axial direction along a direction in which the wall is to be supported, and a radial direction perpendicular to the axial direction. The structural member includes a gas introduction path which is formed to be exposed at a tip end of the structural member and penetrate an inside of the structural member along the axial direction, a first gap which is formed to be concaved in the radial direction to communicate with the gas introduction path through a first hole, and a second hole which is formed to communicate with the gas introduction path at a position more distant from the tip end than the first hole along the axial direction.