PURPOSE: To supply a stable quantity of air in either of the opening and closing states of a valve by making air collide against jetted fuel for atomizing the fuel.

CONSTITUTION: A needle valve 1 which can abut against the valve seat 4b of an injector body 4 has a cylindrical pintle 23 to regulate fuel in cooperation with a fuel jetting hole 21 at its tip. A sleeve 41 which is press-fitted and fixed to the outer peripheral wall on the side of the fuel nozzle hole 21 of the injector body 4 has air holes 63, 64 to introduce air around the pintle 23 and an air- mixed-fuel nozzle 47 for jetting air led in through the air holes 63, 64 and fuel led in through a fuel nozzle hole 21. The air-mixed-fuel nozzle hole 47 is composed of a conical face 48 and a cylindrical face 49, and has such a passage form as the effective diameter of the air-mixed-fuel nozzle hole grows larger as the lift of the needle valve 1 becomes larger.