-----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,
 RA6q2q4sU5j5ihaKPZ4fci55Ks4tH9Uf2KslYxTGDjF7jejC2tJTrbw9koZBN5l3
 bRS+Lfg/3Kp9xR/EIs8EjQ==

<SEC-DOCUMENT>0001126328-08-000204.txt : 20080616
<SEC-HEADER>0001126328-08-000204.hdr.sgml : 20080616
<ACCEPTANCE-DATETIME>20080616130910
ACCESSION NUMBER:		0001126328-08-000204
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080613
FILED AS OF DATE:		20080616
DATE AS OF CHANGE:		20080616

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PRINCIPAL FINANCIAL GROUP INC
		CENTRAL INDEX KEY:			0001126328
		STANDARD INDUSTRIAL CLASSIFICATION:	ACCIDENT & HEALTH INSURANCE [6321]
		IRS NUMBER:				421520346
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		711 HIGH STREET
		CITY:			DES MOINES
		STATE:			IA
		ZIP:			50392-0300
		BUSINESS PHONE:		5152475111

	MAIL ADDRESS:	
		STREET 1:		711 HIGH STREET
		CITY:			DES MOINES
		STATE:			IA
		ZIP:			50392-0300

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			TALLETT ELIZEBETH E
		CENTRAL INDEX KEY:			0001192460

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-16725
		FILM NUMBER:		08900023

	BUSINESS ADDRESS:	
		STREET 1:		C/O VARIAN SEMICONDUCTOR EQUIPMENT
		STREET 2:		35 DORY ROAD
		CITY:			GLOUCESTER
		STATE:			MA
		ZIP:			01930
		BUSINESS PHONE:		9782822000
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-06-13</periodOfReport>

    <issuer>
        <issuerCik>0001126328</issuerCik>
        <issuerName>PRINCIPAL FINANCIAL GROUP INC</issuerName>
        <issuerTradingSymbol>PFG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001192460</rptOwnerCik>
            <rptOwnerName>TALLETT ELIZEBETH E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>711 HIGH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DES MOINES</rptOwnerCity>
            <rptOwnerState>IA</rptOwnerState>
            <rptOwnerZipCode>50392</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-06-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>191.5</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>50.65</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>191.5</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2328.1</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The units convert to common stock on a one-for-one basis.</footnote>
        <footnote id="F2">The reported phantom stock units were acquired pursuant to the Principal Deferred Compensation Plan for Non-Employee Directors and will be settled on the reporting person's retirement.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Joyce N. Hoffman, by Power of Attorney</signatureName>
        <signatureDate>2008-06-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----