<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2002-05-01</periodOfReport>

    <dateOfOriginalSubmission>2002-05-08</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000057131</issuerCik>
        <issuerName>LA-Z-BOY INC</issuerName>
        <issuerTradingSymbol>LZB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001246402</rptOwnerCik>
            <rptOwnerName>RICCIO LOUIS M JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1284 N. TELEGRAPH</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MONROE</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>48162</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior VP and CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>34.33</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2000-01-31</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2003-02-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>315</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>14.62</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2000-01-31</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2004-10-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>630</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9.54</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2000-01-31</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2006-05-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2360</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>13.25</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2000-01-31</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2007-03-06</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2360</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>24.69</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2000-01-31</value>
                <footnoteId id="F1"/>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2008-05-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1180</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>16.42</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2000-01-31</value>
                <footnoteId id="F1"/>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2009-04-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1180</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>15.50</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2001-07-31</value>
                <footnoteId id="F1"/>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2005-07-31</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1310</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>19.80</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2002-08-15</value>
                <footnoteId id="F1"/>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2006-08-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">These shares were omitted from the reporting person's original Form 3.</footnote>
        <footnote id="F2">These were granted under the Replacement Plan for LADD stock options and exercisable as of the reporting date (5/1/2002).</footnote>
        <footnote id="F3">These were granted under the 1997 Incentive Stock Option Plan and become exercisable in four equal installments beginning on the date shown in the Date Exercisable column.</footnote>
        <footnote id="F4">These were granted under the Replacement Plan for LADD stock options and 885 shares are exercisable as of the reporting date (5/1/2002), 295 shares are exercisable 5/7/2002.</footnote>
        <footnote id="F5">These were granted under the Replacement Plan for LADD stock options and 885 shares are exercisable as of the reporting date (5/1/2002), 295 shares are exercisable 4/29/2003.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>James P. Klarr, Attorney-in-fact for Louis M. Riccio, Jr.</signatureName>
        <signatureDate>2008-06-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
