<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
  <headerData>
    <submissionType>144</submissionType>
    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001165098</cik>
          <ccc>XXXXXXXX</ccc>
        </filerCredentials>
      </filer>
      <liveTestFlag>LIVE</liveTestFlag>



    </filerInfo>
  </headerData>
  <formData>
    <issuerInfo>
      <issuerCik>0001145255</issuerCik>
      <issuerName>HENNESSY ADVISORS INC</issuerName>
      <secFileNumber>001-36423</secFileNumber>
      <issuerAddress>
        <com:street1>7250 REDWOOD BLVD.</com:street1>
        <com:street2>SUITE 200</com:street2>
        <com:city>NOVATO</com:city>
        <com:stateOrCountry>CA</com:stateOrCountry>
        <com:zipCode>94945</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>415-899-1555</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>NILSEN TERESA M</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Member of immediate family of any of the foregoing</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Charles Schwab Corporation</name>
        <address>
          <com:street1>3000 Schwab Way</com:street1>
          <com:city>Westlake</com:city>
          <com:stateOrCountry>TX</com:stateOrCountry>
          <com:zipCode>76262</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>19860</noOfUnitsSold>
      <aggregateMarketValue>209721.00</aggregateMarketValue>
      <noOfUnitsOutstanding>7783737</noOfUnitsOutstanding>
      <approxSaleDate>03/18/2025</approxSaleDate>
      <securitiesExchangeName>Nasdaq</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>06/13/2003</acquiredDate>
      <natureOfAcquisitionTransaction>Gifted</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Teresa M Nilsen</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>Y</isGiftTransaction>
      <donarAcquiredDate>12/31/2000</donarAcquiredDate>
      <amountOfSecuritiesAcquired>19860</amountOfSecuritiesAcquired>
      <paymentDate>06/13/2003</paymentDate>
      <natureOfPayment>n/a</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <remarks>Table 1 information - 9,930 shares are being sold out of Christopher G. Nilsen's account - 9,050 shares were gifted - 06.13.2003 - 09.25.2024 - 880 shares were stock splits - 03.08.2005 - 03.06.2017 Table 1 information - 9,930 shares are being sold out of Anthony M. Nilsen's account - 9,050 shares were gifted - 06.13.2003 - 09.25.2024 - 880 shares were stock splits - 03.08.2005 - 03.06.2017</remarks>
    <noticeSignature>
      <noticeDate>03/18/2025</noticeDate>
      <signature>Teresa M Nilsen</signature>
    </noticeSignature>
  </formData>
</edgarSubmission>
[{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 3253}]
144
0001165098
XXXXXXXX
LIVE
0001145255
HENNESSY ADVISORS INC
001-36423
7250 REDWOOD BLVD.
SUITE 200
NOVATO
CA
94945
415-899-1555
NILSEN TERESA M
Member of immediate family of any of the foregoing
Common
Charles Schwab Corporation
3000 Schwab Way
Westlake
TX
76262
19860
209721.00
7783737
03/18/2025
Nasdaq
Common
06/13/2003
Gifted
Teresa M Nilsen
Y
12/31/2000
19860
06/13/2003
n/a
Y
Table 1 information - 9,930 shares are being sold out of Christopher G. Nilsen's account - 9,050 shares were gifted - 06.13.2003 - 09.25.2024 - 880 shares were stock splits - 03.08.2005 - 03.06.2017 Table 1 information - 9,930 shares are being sold out of Anthony M. Nilsen's account - 9,050 shares were gifted - 06.13.2003 - 09.25.2024 - 880 shares were stock splits - 03.08.2005 - 03.06.2017
03/18/2025
Teresa M Nilsen