To prevent leakage of fuel gas from an injector, by arranging on a fuel rail, an opening/closing control means by which a leakage preventing valve is controlled to open and close the inflow opening of the injector.

Leakage preventing valves 16 by which the inflow openings 5a of injectors 5 are opened and closed, are arranged in a fuel rail 1. Opening/ closing control means 11 by which the leakage preventing valves 16 are controlled to be opened and closed, is arranged on the fuel rail 1. The opening/ closing control means 11 is operated to be opened by switching on an ignition switch 13. When an engine is stopped by switching off the ignition switch 13, the opening/closing control means 11 is operated to be closed, and the leakage preventing valves 16 close the inflow openings 5b of the injectors 5. This leakage preventing valves 16 are burdened with gas leakage prevention only, and control valves in the injectors 5 are burdened with the precision control of a fuel injection amount. By this way, leakage of fuel gas from the injectors can be prevented certainly.