Exhibit 13.1

                   CERTIFICATION OF PERIODIC FINANCIAL REPORT
                       PURSUANT TO 18 U.S.C. SECTION 1350

      In connection with the Annual Report of Siliconware Precision Industries
Co., Ltd. (the "Company") on Form 20-F for the year ended December 31, 2003 as
filed with the Securities and Exchange Commission on the date hereof (the
"Report"), I, Chi Wen Tsai, the Chief Executive Officer of the Company, hereby
certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906
of the Sarbanes-Oxley Act of 2002, to the best of my knowledge, that:

      1.    The Report fully complies with the requirements of Section 13(a) or
15(d) of the Securities Exchange Act of 1934; and

      2.    The information contained in the Report fairly presents, in all
material respects, the financial condition and results of operations of the
Company.

Date: June 28, 2004

                                        By:       /s/ Chi Wen Tsai
                                               ---------------------------------
                                        Name:  Chi Wen Tsai
                                        Title: Chief Executive Officer

*     A signed original of this written statement required by Section 906 of the
      Sarbanes-Oxley Act of 2002 has been provided to the Company and will be
      retained by the Company and furnished to the Securities and Exchange
      Commission or its staff upon request.