-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 43qwJUtuX5rfv7JF3geSrQ==

<SEC-DOCUMENT>0001179019-04-000018.txt : 20041108
<SEC-HEADER>0001179019-04-000018.hdr.sgml : 20041108
<ACCEPTANCE-DATETIME>20041108171524
ACCESSION NUMBER:		0001179019-04-000018
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20041105
FILED AS OF DATE:		20041108
DATE AS OF CHANGE:		20041108

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			QUESTAR CORP
		CENTRAL INDEX KEY:			0000751652
		STANDARD INDUSTRIAL CLASSIFICATION:	NATURAL GAS TRANSMISSION & DISTRIBUTION [4923]
		IRS NUMBER:				870407509
		STATE OF INCORPORATION:			UT
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		180 EAST 100 SOUTH ST
		STREET 2:		PO BOX 45433
		CITY:			SALT LAKE CITY
		STATE:			UT
		ZIP:			84145
		BUSINESS PHONE:		8015345000

	MAIL ADDRESS:	
		STREET 1:		180 EAST 100 SOUTH ST
		STREET 2:		P O BOX 45433
		CITY:			SALT LAKE CITY
		STATE:			UT
		ZIP:			84145

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			PARKS S E
		CENTRAL INDEX KEY:			0001179019

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08796
		FILM NUMBER:		041126630

	BUSINESS ADDRESS:	
		STREET 1:		180 EAST 100 SOUTH
		STREET 2:		P O BOX 45601
		CITY:			SALT LAKE CITY
		STATE:			UT
		ZIP:			84145-0601
		BUSINESS PHONE:		8013245497

	MAIL ADDRESS:	
		STREET 1:		180 EAST 100 SOUTH
		CITY:			SALT LAKE CITY
		STATE:			UT
		ZIP:			84111
</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>2004-11-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000751652</issuerCik>
        <issuerName>QUESTAR CORP</issuerName>
        <issuerTradingSymbol>STR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001179019</rptOwnerCik>
            <rptOwnerName>PARKS S E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>180 EAST 100 SOUTH</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SALT LAKE CITY</rptOwnerCity>
            <rptOwnerState>UT</rptOwnerState>
            <rptOwnerZipCode>84111</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. VP, and CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock and attached Common Stock Purchase Rights</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>82712</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock and attached Common Stock Purchase Rights</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>22484.3237</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Employee Investment Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>48.22</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-11-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4.4795</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>48.22</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Phantom Stock Units</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4.4795</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4028.9018</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeHolding>
            <securityTitle>
                <value>Common Stock and attached Common Stock Purchase Rights</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock and attached Common Stock Purchase Rights</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>229748</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">As of November 5, 2004, I have 22,484.3237 equivalent shares of stock in Questar's Employee Investment Plan.  The number of equivalent shares will fluctuate as Questar's stock price changes; this fluctuation does not reflect any transactions that should be reported.  My last account balance as of October 7, 2004, was incorrectly reported by the plan administrator.</footnote>
        <footnote id="F2">Phantom stock units will be converted to cash beginning at retirement; my retirement date is unknown.</footnote>
        <footnote id="F3">I receive phantom stock units as a result of my participation in an excess benefit plan.  This total includes 2,438.6347 units in such plan in addition to units held through my account balance in a deferred compensation plan.</footnote>
        <footnote id="F4">The question about dates is irrelevant since I am not reporting any changes in my stock options.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Connie C. Holbrook Attorney in Fact for S.E. Parks</signatureName>
        <signatureDate>2004-11-08</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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