To provide a fuel injector which stably keeps an air-fuel ratio for a model engine used under severe conditions and has excellent responsiveness.

A magnetic core 32 is inserted into a solenoid coil 32 in an equipment body 31. A fuel-feed passage 35 is in the magnetic core 34. A movable valve element 38 which is magnetically attracted by the magnetic core 34 is in the coil 32 in the equipment body 31. The valve element 38 has a flow passage 39 communicating with the feed passage 35. The valve element 38 is urged by a flat spring 44 to be brought into contact with a valve cage 36, to close a fuel injection port 37. Used fuel is pressurized at low pressures of 20 to 100kPa which are equal to the pressure in the crankcase in a model engine. The moving direction of the valve element 38 in a fuel injector 30 is made parallel to the traveling direction of a model plane, and the fuel injection port 37 of the fuel injector 30 is made to be directed forward in the traveling direction of the model plane. At rapid acceleration of the engine, the movement of the valve element 38 in its attracted direction by the magnetic core 34 is urged by the movement of the model plane itself. As a result of which, excellent responsiveness is obtained and the amount of fuel supplied rapidly increases. Even at deceleration, the same effects can be obtained.