SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 6-K

                        REPORT OF FOREIGN PRIVATE ISSUER
                    PURSUANT TO RULE 13a-16 OR 15d-16 UNDER
                      THE SECURITIES EXCHANGE ACT OF 1934

                        For the month of September, 2004

                        Commission File Number: 1-13368

                                     POSCO
                (Translation of registrant's name into English)

       POSCO Center, 892 Daechi 4-dong, Kangnam-gu, Seoul, Korea, 135-777
                    (Address of principal executive office)

(Indicate by check mark whether the registrant files or will file annual reports
under cover of Form 20-F or Form 40-F.)

                   Form 20-F [ x ]          Form 40-F [   ]
                              ---                      ---

[Indicate by check mark whether the registrant by furnishing the information
contained in this Form is also thereby furnishing the information to the
Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

                      Yes [   ]                No [ x ]
                           ---                     ---

[If "Yes" is marked, indicate below the file number assigned to the registrant
in connection with Rule 12g3-2(b) : 82-                      .]
                                       ----------------------



POSCO is furnishing under cover of Form 6-K :

EXHIBITION 99.1 : An English-language translation of documents with respect to
                  the Addition of an affiliated company dated as of September
                  15, 2004.



                                   SIGNATURES

     Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorized.



                                               POSCO
                                               -----
                                               (Registrant)



Date   September 15, 2004                      By   /s/ Cho, Jae-Ku
-----------------------------                  ---------------------------------
* Print the name and title under the           (Signature)*
  signature of the signing officer.            Name:  Cho, Jae-Ku
                                               Title: General Manager of Finance
                                                      Management Department