Exhibit 12.1
 CERTIFICATIONS
  1.
    
    I have reviewed this annual report on Form 20-F of Taiwan Semiconductor
Manufacturing Company Limited;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(s) 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)) and internal control over financial
reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) 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 annual report is being
prepared;(b)
    
    Designed such internal control over financial reporting, or
caused such internal control over financial reporting to be designed under our
supervision, to provide reasonable assurance regarding the reliability of
financial reporting and the preparation of financial statements for external
purposes in accordance with generally accepted accounting principles;(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(s) 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 companys board of directors (or persons
performing the equivalent function):
 (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:  April 17, 2009
    By:
    /s/ Rick TsaiName:
    Rick TsaiTitle:
    Chief Executive Officer