Exhibit 12.1



CERTIFICATION



I, Toshio Maruyama, certify that:



|1. | I have reviewed this annual report on Form 20-F/A Amendment No. 1 of Advantest Corporation (the registrant);
|-- | --------------------------------------------------------------------------------------------------------------



|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 registrant as of, and for, the periods presented in this report;
|-- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



|4. | The registrants other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e)
of the Securities Exchange Act of 1934) for the registrant and have:
|-- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | (a) | Designed such disclosure controls and procedures to ensure that material information relating to the registrant, 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) | Evaluated the effectiveness of the registrant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
| | --- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | (c) | Disclosed in this report any change in the registrant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 registrants internal control over financial reporting; and
| | --- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



|5. | The registrants other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrants
auditors and the audit committee of the registrants board of directors (and 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
registrant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 registrants internal control over financial reporting.
| | --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------



Date: September 29, 2005



ADVANTEST CORPORATIONBy:

/s/    TOSHIO MARUYAMAName:

Toshio MaruyamaTitle:

Representative Board Director, President and CEO




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CERTIFICATION



I, Hitoshi Owada, certify that:



|1. | I have reviewed this annual report on Form 20-F/A Amendment No. 1 of Advantest Corporation (the registrant);
|-- | --------------------------------------------------------------------------------------------------------------



|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 registrant as of, and for, the periods presented in this report;
|-- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



|4. | The registrants other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e)
of the Securities Exchange Act of 1934) for the registrant and have:
|-- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | (a) | Designed such disclosure controls and procedures to ensure that material information relating to the registrant, 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) | Evaluated the effectiveness of the registrant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
| | --- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | (c) | Disclosed in this report any change in the registrant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 registrants internal control over financial reporting; and
| | --- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



|5. | The registrants other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrants
auditors and the audit committee of the registrants board of directors (and 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
registrant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 registrants internal control over financial reporting.
| | --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------



Date: September 29, 2005



ADVANTEST CORPORATIONBy:

/s/    HITOSHI OWADAName:

Hitoshi OwadaTitle:

Director and Managing Executive Officer