Fuel tank and manufacturing method thereof

In the fuel tank (10), a tank wall (12) providing a tank chamber (12S) is formed by blow molding. A tank partition (22) is disposed in the tank chamber (12S). The tank partition (22) is positioned in a direction substantially perpendicular to a longitudinal direction of the tank wall (12), and is clamped between the opposite inner surfaces of the tank wall (12). A functional component (30) is attached to the tank partition (22).