A two-stage fuel injection valve for injecting a fuel into a combustion chamber of a cylinder head, characterized in that the valve comprises: a valve body (100a, 3000) having a plurality of main fuel nozzle holes (202, 3302) and a plurality of auxiliary fuel nozzle holes (204, 3304) radially formed at points axially spaced apart from the front end based on the same center axis, a main fuel inflow passage (110, 210, 3110, 3120, 3210, 3310) formed from a main fuel inlet to a point adjacent to the main fuel nozzle hole (202, 3302), a first main fuel chamber (206, 3206) axially formed to communicate with the main fuel inflow passage (110, 210, 3110, 3120, 3210, 3310), an auxiliary fuel inflow passage (120, 220, 3130, 3220) formed from an auxiliary fuel inlet to a point adjacent to the auxiliary fuel nozzle hole (204, 3304), and an auxiliary fuel discharge passage formed from another point adjacent to the auxiliary fuel nozzle hole (204, 3304); a plunger (300, 3400) inserted into the first main fuel chamber (206, 3206) of the valve body (100a, 3000) to be axially slidable so that an auxiliary fuel pressurizing chamber (302, 3306) is formed between the front end and the valve body (100a, 3000) to communicate with the auxiliary fuel nozzle hole (204, 3304), advancing forwards with the pressure of a main fuel applied to the first main fuel chamber (206, 3206) to pressurize an auxiliary fuel in the auxiliary fuel pressurizing chamber (302, 3306), and allowing the main fuel inflow passage (110, 210, 3110, 3120, 3210, 3310) to communicate with the main fuel nozzle hole (202, 3302) after an auxiliary fuel injection completion point; a plunger spring (500, 3600) for elastically pressurizing the plunger (300, 3400) in a retreating direction; a needle (400, 3500) inserted into the center of the plunger (300, 3400) to be slidable in an axial direction, the needle (400, 3500) having a needle end (410, 3510) at the front end thereof to close the auxiliary fuel nozzle hole (204, 3304), the needle (400, 3500) retreating by means of pressure increase of the auxiliary fuel pressurizing chamber (302, 3306) so that the auxiliary fuel pressurizing chamber (302, 3306) communicates with the auxiliary fuel nozzle hole (204, 3304); and a needle spring (600, 3650) interposed between the rear end of the needle (400, 3500) and the plunger (300, 3400) to elastically pressurize the needle (400, 3500) in the advancing direction. a valve body (100a, 3000) having a plurality of main fuel nozzle holes (202, 3302) and a plurality of auxiliary fuel nozzle holes (204, 3304) radially formed at points axially spaced apart from the front end based on the same center axis, a main fuel inflow passage (110, 210, 3110, 3120, 3210, 3310) formed from a main fuel inlet to a point adjacent to the main fuel nozzle hole (202, 3302), a first main fuel chamber (206, 3206) axially formed to communicate with the main fuel inflow passage (110, 210, 3110, 3120, 3210, 3310), an auxiliary fuel inflow passage (120, 220, 3130, 3220) formed from an auxiliary fuel inlet to a point adjacent to the auxiliary fuel nozzle hole (204, 3304), and an auxiliary fuel discharge passage formed from another point adjacent to the auxiliary fuel nozzle hole (204, 3304); a plunger (300, 3400) inserted into the first main fuel chamber (206, 3206) of the valve body (100a, 3000) to be axially slidable so that an auxiliary fuel pressurizing chamber (302, 3306) is formed between the front end and the valve body (100a, 3000) to communicate with the auxiliary fuel nozzle hole (204, 3304), advancing forwards with the pressure of a main fuel applied to the first main fuel chamber (206, 3206) to pressurize an auxiliary fuel in the auxiliary fuel pressurizing chamber (302, 3306), and allowing the main fuel inflow passage (110, 210, 3110, 3120, 3210, 3310) to communicate with the main fuel nozzle hole (202, 3302) after an auxiliary fuel injection completion point; a plunger spring (500, 3600) for elastically pressurizing the plunger (300, 3400) in a retreating direction; a needle (400, 3500) inserted into the center of the plunger (300, 3400) to be slidable in an axial direction, the needle (400, 3500) having a needle end (410, 3510) at the front end thereof to close the auxiliary fuel nozzle hole (204, 3304), the needle (400, 3500) retreating by means of pressure increase of the auxiliary fuel pressurizing chamber (302, 3306) so that the auxiliary fuel pressurizing chamber (302, 3306) communicates with the auxiliary fuel nozzle hole (204, 3304); and a needle spring (600, 3650) interposed between the rear end of the needle (400, 3500) and the plunger (300, 3400) to elastically pressurize the needle (400, 3500) in the advancing direction.