To accurately control an injection amount in an initial period of injection of a hydraulic operation fuel injector with a single solenoid.

A single solenoid 130 is arranged on an injector main body. A first valve member is so arranged as to shift between a first position where an operation fluid inlet 106 is opened to an operation fluid cavity 109 and a second position where it is closed based on operation of the solenoid. A needle valve member 160 is arranged so as to shift between a position where a nozzle outlet 117 is opened and a position where it is interrupted. The needle valve member has a closing hydraulic surface 167 exposed into a needle controlling chamber 118. A second valve member is arranged so as to move an OFF-position where the needle controlling chamber is opened to a high pressure fluid source and an ON-position where it is opened to a low pressure fluid passage based on the operation of the solenoid. An injection amount profile of the fuel injector is desirably controlled by switching current to the solenoid between high attractin current and an intermediate holding current.