To facilitate regulation of an idling position of measuring needle for controlling a rate of fuel which flows from a fuel nozzle.

A regulating screw 17 is screwed around a screw hole 15 of a restriction valve shaft 8 for rotating a cylindrical restriction valve 4, and is connected to a regulating part piece 19 by a screw having a pitch which is different from the pitch of the regulating screw 17. A measuring needle 7 is integratedly moved in a center axial direction freely to move the regulating part piece 19 in the center axial direction and to prevent rotation of the regulating part piece 19. When the regulating screw 17 is rotated, the regulating part piece 19 is displaced for a distance corresponding to a difference between pitches, and the position of the measuring needle 7 is finely regulated if the regulating screw 17 is rotated largely.