The present invention relates to a method and apparatus for post-injection molding processing a nipple and a connector for a liquefied powder milk bottle. The method of the present invention comprises: an air cleaning step (steps S1, S1&prime；) of removing alien substances or residual materials coated on the surface of the nipple or the connector by air injection in a sanitization process as a process of post-injection molding processing the connector (4) which is injection molded to form a screw in the inner surface thereof so that the screw is coupled to an inlet portion (2) of the bottle (1) containing liquefied powder milk, and the nipple (5) which is formed to be coupled to the connector； a testing step (S5, S5&prime；) of testing the nipple or the connector by a magnifying glass； an assembling step (S6) of assembling the nipple and the connector； a packing step (S7) of vacuum packing the assembled nipple and connector； an inspection step (S8) of inspecting the vacuum packed nipple and connector； and a sterilization step (S9) of sterilizing the inspected nipple and connector. The method further comprises a drying step (steps S4, S4&prime；) of, in addition to a washing process by the air cleaning step (steps S1, S1&prime；), continuously passing through at least one washing step (steps S2, S2&prime；, S3, S3&prime；) which puts the nipple or the connector into a storage container (45) storing the nipple or the connector in a processing apparatus (10) for performing a precision sanitization process, rotates the nipple or the connector in the storage container in a state that the storage container is submerged into washing water, and washes the nipple or the connector, and then supplying air to dry the washed nipple or connector. Therefore, the method of the present invention has effects that a strict sanitization process can be efficiently performed on an injection-molded nipple and connectors for coupling the nipple to a liquefied powder milk storage container, and
