Exhibit 12(a)


                                 Certification

     I, Jason C.S. Chang, Chief Executive Officer of Advanced Semiconductor
Engineering, Inc. ("ASE Inc."), certify that:

          1. I have reviewed this annual report on Form 20-F of ASE Inc.;

          2. Based on my knowledge, this report does not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
the statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this report;

          3. Based on my knowledge, the financial statements, and other
financial information included in this report, fairly present in all material
respects the financial condition, results of operations and cash flows of the
company as of, and for, the periods presented in this report;

          4. The company's other certifying officer and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) for the company and have:

               (a) Designed such disclosure controls and procedures, or caused
     such disclosure controls and procedures to be designed under our
     supervision, to ensure that material information relating to the company,
     including its consolidated subsidiaries, is made known to us by others
     within those entities, particularly during the period in which this report
     is being prepared;

               (b) [Reserved]

               (c) Evaluated the effectiveness of the company's disclosure
     controls and procedures and presented in this report our conclusions about
     the effectiveness of the disclosure controls and procedures, as of the end
     of the period covered by this report based on such evaluation; and

               (d) Disclosed in this report any change in the company's
     internal control over financial reporting that occurred during the period
     covered by the annual report that has materially affected, or is
     reasonably likely to materially affect, the company's internal control
     over financial reporting; and

          5. The company's other certifying officer and I have disclosed,
based on our most recent evaluation of internal control over financial
reporting, to the company's auditors and the audit committee of the company's
board of directors (or persons performing the equivalent functions):

               (a) All significant deficiencies and material weaknesses in the
     design or operation of internal control over financial reporting which are
     reasonably likely to adversely affect the company's ability to record,
     process, summarize and report financial information; and

               (b) Any fraud, whether or not material, that involves management
     or other employees who have a significant role in the company's internal
     control over financial reporting.

Date: June 30, 2004



                                       /s/ Jason C.S. Chang
                                       ----------------------------------------
                                       Jason C.S. Chang
                                       Chief Executive Officer