<SUBMISSION>
<ACCESSION-NUMBER>0001111928-09-000088
<TYPE>4/A
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20090303
<FILING-DATE>20090917
<DATE-OF-FILING-DATE-CHANGE>20090917
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>GAPONTSEV VALENTIN P
<CIK>0001130421
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4/A
<ACT>34
<FILE-NUMBER>001-33155
<FILM-NUMBER>091074656
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>660 MAIN STREET
<CITY>STURBRIDGE
<STATE>MA
<ZIP>01566
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>IPG PHOTONICS CORP
<CIK>0001111928
<ASSIGNED-SIC>3674
<IRS-NUMBER>043444218
<STATE-OF-INCORPORATION>DE
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>50 OLD WEBSTER ROAD
<CITY>OXFORD
<STATE>MA
<ZIP>01540
<PHONE>5083731100
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>50 OLD WEBSTER ROAD
<CITY>OXFORD
<STATE>MA
<ZIP>01540
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2009-03-03</periodOfReport>

    <dateOfOriginalSubmission>2009-03-04</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0001111928</issuerCik>
        <issuerName>IPG PHOTONICS CORP</issuerName>
        <issuerTradingSymbol>IPGP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001130421</rptOwnerCik>
            <rptOwnerName>GAPONTSEV VALENTIN P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O IPG PHOTONICS CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>50 OLD WEBSTER ROAD</rptOwnerStreet2>
            <rptOwnerCity>OXFORD</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01540</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO &amp; Chairman of the Board</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-03-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>247690</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11942931</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Acquired pursuant to the Agreement and Plan of Reorganization, dated August 5, 2008.  Under such Agreement, the reporting person sold his minority interest in NTO IRE-Polus to the Issuer for a purchase price of $5,169,300.  The issuer issued 247,690 shares of common stock in payment of the purchase price.  The closing occurred on March 3, 2009.</footnote>
        <footnote id="F2">This amended Form 4 is being filed to correct the Amount of Securities Beneficially Owned Following Reported Transaction(s) in Column 5 in Table I.  The amounts reported in Column 5 on Table I on the Forms 4 filed by the Reporting Person on 4/1/09 and 5/22/09 also did not accurately reflect the amount of securities beneficially owned and each overstated by 49,668 shares the Amount of Securities Beneficially Owned Following Reported Transaction(s) in Column 5.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Angelo P. Lopresti, Attorney-at-law</signatureName>
        <signatureDate>2009-09-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
