An injector for injecting fuel, which is introduced from a fuel rail, into an engine to supply the fuel thereto is provided. In particular, the injector includes a housing, an electromagnetic generation unit accommodated in the housing and formed to generate an electromagnetic field when electric power is applied thereto, a core inserted into a fuel-rail-side end of a bobbin to form a magnetic circuit using the generated electromagnetic field, a lead pipe inserted into an engine-side end of the bobbin to form the magnetic circuit by coupling with the core, a molding unit formed to enclose the electromagnetic generation unit and an outer peripheral surface of the core to block introduction of moisture, and a cover coupled to the outer peripheral surface of the core to constitute the magnetic circuit together with the core.