-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 EBVsMY2VxqPpamnfBo9nntebR73RlbU3Q1CVCfTASYoY3ZMFLZS45rI5Yp6jzQcP
 74um+3HuI7YcfT2SxZrd+w==

<SEC-DOCUMENT>0000078460-07-000049.txt : 20070417
<SEC-HEADER>0000078460-07-000049.hdr.sgml : 20070417
<ACCEPTANCE-DATETIME>20070417170813
ACCESSION NUMBER:		0000078460-07-000049
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20070413
FILED AS OF DATE:		20070417
DATE AS OF CHANGE:		20070417

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SHI DAVID E
		CENTRAL INDEX KEY:			0001068735
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		STATE OF INCORPORATION:			NC
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-06196
		FILM NUMBER:		07771525

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		8642942100

	MAIL ADDRESS:	
		STREET 1:		FURMAN UNIVERSITY
		STREET 2:		3300 POINSETT HIGHWAY
		CITY:			GREENVILLE
		STATE:			SC
		ZIP:			29613

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PIEDMONT NATURAL GAS CO INC
		CENTRAL INDEX KEY:			0000078460
		STANDARD INDUSTRIAL CLASSIFICATION:	NATURAL GAS DISTRIBUTION [4924]
		IRS NUMBER:				560556998
		STATE OF INCORPORATION:			NC
		FISCAL YEAR END:			1031

	BUSINESS ADDRESS:	
		STREET 1:		4720 PIEDMONT ROW DR
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28210
		BUSINESS PHONE:		7043643120

	MAIL ADDRESS:	
		STREET 1:		P.O. BOX 33068
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28233
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-04-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000078460</issuerCik>
        <issuerName>PIEDMONT NATURAL GAS CO INC</issuerName>
        <issuerTradingSymbol>PNY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001068735</rptOwnerCik>
            <rptOwnerName>SHI DAVID E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O PIEDMONT NATURAL GAS</rptOwnerStreet1>
            <rptOwnerStreet2>PO BOX 33068</rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28233</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2007-04-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>299.982</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>27.085</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10650.768</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>660</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>IRA</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Purchased in accordance with election to invest director fees in issuer's stock through issuer's Dividend Reinvestment and Stock Purchase Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Judy Z. Mayo by limited power of attorney for David E. Shi</signatureName>
        <signatureDate>2007-04-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----