The present invention relates to a fuel injection valve for an internal combustion engine, in which both a main needle and a pilot needle are opened or only the pilot needle is opened by compressed high-pressure fuel oil or compressed air, thereby enabling main injection and pilot injection to be separately performed by the single fuel-injection valve. The fuel injection valve of the present invention comprises: a valve body; a nozzle coupled to a lower end of the valve body; a valve plate which is installed in the valve body and which has a compressed air chamber formed in the upper portion thereof; a main needle spindle arranged at the lower end of the valve plate; a main needle which is arranged in the nozzle, such that the main needle is positioned at the lower end of the main needle spindle, which opens a flow channel formed in the nozzle by supplied compressed fuel oil so as to inject fuel through a main injection hole, and which has a pilot supply port; a main needle spring interposed between the main needle spindle and the valve plate; a spring plate, the lower portion of which is inserted into the valve plate, and in the upper portion of which an air supply hole is formed so as to supply air into the compressed air chamber; a pilot needle spring positioned at the lower end of the spring plate; a pilot needle spindle positioned at the lower end of the pilot needle spring; and a pilot needle which is arranged at the main needle, such that the pilot needle is positioned at the lower end of the pilot needle spindle, and which operates by the fuel oil supplied through the pilot supply port of the main needle so as to open a flow channel formed in the main needle in order to inject fuel through a pilot injection hole.