-----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,
 GF8h/fbaxqvEmCN9tYW9o6wNyGclF2WN5f2gS3wLyDjh5iM4dYSp0+HB50Jeu/UC
 Nw1Sw/iAodBHuc6tsUa3KQ==

<SEC-DOCUMENT>0001229255-10-000001.txt : 20100601
<SEC-HEADER>0001229255-10-000001.hdr.sgml : 20100531
<ACCEPTANCE-DATETIME>20100601111603
ACCESSION NUMBER:		0001229255-10-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100528
FILED AS OF DATE:		20100601
DATE AS OF CHANGE:		20100601

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			LIEBLE RANDY F
		CENTRAL INDEX KEY:			0001229255

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-02451
		FILM NUMBER:		10868510

	MAIL ADDRESS:	
		STREET 1:		3925 N HASTINGS WAY
		CITY:			EAU CLAIRE
		STATE:			WI
		ZIP:			54703

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NATIONAL PRESTO INDUSTRIES INC
		CENTRAL INDEX KEY:			0000080172
		STANDARD INDUSTRIAL CLASSIFICATION:	ORDNANCE & ACCESSORIES, (NO VEHICLES/GUIDED MISSILES) [3480]
		IRS NUMBER:				390494170
		STATE OF INCORPORATION:			WI
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3925 N HASTINGS WAY
		CITY:			EAU CLAIRE
		STATE:			WI
		ZIP:			54703
		BUSINESS PHONE:		7158392121

	MAIL ADDRESS:	
		STREET 1:		3925 N HASTINGS WAY
		CITY:			EAU CLAIRE
		STATE:			WI
		ZIP:			54703

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NATIONAL PRESSURE COOKER CO
		DATE OF NAME CHANGE:	19710509
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-05-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000080172</issuerCik>
        <issuerName>NATIONAL PRESTO INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>NPK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001229255</rptOwnerCik>
            <rptOwnerName>LIEBLE RANDY F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3925 N HASTINGS WAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>EAU CLAIRE</rptOwnerCity>
            <rptOwnerState>WI</rptOwnerState>
            <rptOwnerZipCode>54703</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President,Treasurer,CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock $1.00 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2010-05-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>200</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>97.71</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>824</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common stock $1.00 par value</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>116</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401(k) Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>Norma L Jaenke</signatureName>
        <signatureDate>2010-06-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----