To provide a fuel injection device, for example in the form of pump/ injection device, with which a fault according to the conventional arrangement can be reduced.

A fuel injection device is composed of a valve needle which is engaged with a valve seat and biased by a spring 54, a fuel supply line arranged so that the fuel under pressure is supplied to the valve seat, a control chamber 50 which is in communication with the fuel supply line through a passage 52 restricted, and a control valve 66 which arranged so as to control the fuel pressure in the control chamber 50, wherein the chamber 50 is partially bounded by surface (s) in engagement with the valve needle, and the surface is oriented so that a force application is made to the surface on which the impression of a high pressure fuel to the chamber 50 acts in the direction resisting aganist the action of the spring on the valve needle.