<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
    <periodOfReport>2004-01-09</periodOfReport>
    <notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000895421</issuerCik>
        <issuerName>MORGAN STANLEY</issuerName>
        <issuerTradingSymbol>MWD</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001179703</rptOwnerCik>
            <rptOwnerName>KIDDER C ROBERT</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>MORGAN STANLEY</rptOwnerStreet1>
            <rptOwnerStreet2>1585 BROADWAY</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10036</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>2004-01-09</value>
      </transactionDate>
      <transactionCoding>
          <transactionFormType>4</transactionFormType>
          <transactionCode>M</transactionCode>
          <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
      <value />
      </transactionTimeliness>
      <transactionAmounts>
          <transactionShares>
              <value>8000</value>
          </transactionShares>
          <transactionPricePerShare>
              <value>9.75</value>
          </transactionPricePerShare>
          <transactionAcquiredDisposedCode>
              <value>A</value>
          </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <postTransactionAmounts>
          <sharesOwnedFollowingTransaction>
              <value>35574</value>
          </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
          <directOrIndirectOwnership>
              <value>D</value>
          </directOrIndirectOwnership>
      </ownershipNature>
   </nonDerivativeTransaction>
  </nonDerivativeTable>
  <derivativeTable>
   <derivativeTransaction>
      <securityTitle>
          <value>Non-Qualified Stock Option (Right to Buy)</value>
      </securityTitle>
      <conversionOrExercisePrice>
          <value>9.75</value>
      </conversionOrExercisePrice>
      <transactionDate>
          <value>2004-01-09</value>
      </transactionDate>
      <transactionCoding>
          <transactionFormType>4</transactionFormType>
          <transactionCode>M</transactionCode>
          <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionAmounts>
          <transactionShares>
              <value>8000</value>
          </transactionShares>
          <transactionPricePerShare>
              <value>0</value>
          </transactionPricePerShare>
          <transactionAcquiredDisposedCode>
              <value>D</value>
          </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
          <value>1995-05-20</value>
              <footnoteId id="F1" />
      </exerciseDate>
      <expirationDate>
          <value>2004-05-19</value>
      </expirationDate>
      <underlyingSecurity>
          <underlyingSecurityTitle>
              <value>Common Stock</value>
          </underlyingSecurityTitle>
          <underlyingSecurityShares>
              <value>8000</value>
          </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
          <sharesOwnedFollowingTransaction>
              <value>0</value>
          </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
          <directOrIndirectOwnership>
              <value>D</value>
          </directOrIndirectOwnership>
      </ownershipNature>
   </derivativeTransaction>
  </derivativeTable>
<footnotes>
   <footnote id="F1">Options became exercisable in increments of one-third per year for three years.  All are presently exercisable.</footnote>
</footnotes>
<remarks></remarks>    <ownerSignature>
       <signatureName>Charlene R. Herzer, Attorney-In-Fact</signatureName>
       <signatureDate>2004-01-12</signatureDate>
    </ownerSignature>
</ownershipDocument>

