To monitor the function of flow limiters of a fuel quantity adjusting system as easily as possible by inspecting whether or not the flow limiters cut off fuel flow.

Fuel injectors 120-123 are assigned to each cylinder of an internal combustion engine 100. Fuel is adjusted in quantity to the respective fuel injectors 120-123 through magnetic valves 130-133. Fuel is fed to each cylinder of the internal combustion engine 100 from a rail 135 through the fuel injectors 120-123. Flow limiters 180-183 are respectively arranged between the rail 135 and the respective fuel injectors 120-123. These flow limiters 180-183 are so constituted as to cut off connecting parts between the rail 135 and the respective fuel injectors 120-123 in case of fuel of the prescribed quantity or more flowing within the prescribed time. This quantity is selected to be larger than the whole load quantity or start-up quantity and to be smaller than the quantity causing the damage of the internal combustion engine.