Abstract: A unit fuel injector includes a body, the body having a fuel supply and return chamber, a fuel supply passage communicating with the chamber, and a drain passage communicating with the chamber. The body is provided with a pump mechanism, an injection nozzle mechanism for injecting high pressure fuel from the pump mechanism, and an electromagnetic valve mechanism for escaping the high fuel pressure from the pump mechanism. The electromagnetic valve mechanism include a poppet-type valve member. Immediately when a head of the valve member is disengaged from a valve seat facing the fuel supply and return chamber, the pressurized fuel within the pump mechanism is spilled or fed to the fuel supply and return chamber. The unit fuel injector further includes an auxiliary valve mechanism for opening and closing the drain passage. The auxiliary valve mechanism includes a valve port at one end of the drain passage, and when the head of the valve member abuts against a stop portion of the body, the valve port is closed.