EXHIBIT 5

                            FREDRIKSON & BYRON, P.A.
                       900 Second Avenue South, Suite 1100
                          Minneapolis, Minnesota 55402

                            Telephone: (612) 347-7000
                            Facsimile: (612) 347-7077

                                 March 30, 1998


Electro-Sensors, Inc.
6111 Blue Circle Drive
Minnetonka, Minnesota  55343-9108

         Re:  Registration Statement on Form S-8

Ladies/Gentlemen:

     We are acting as corporate counsel to Electro-Sensors, Inc. (the "Company")
in  connection  with the original  registration  by the Company on Form S-8 (the
"Registration  Statement")  under the  Securities  Act of 1933,  as amended (the
"Act") of options and 300,000  shares (the  "Shares") of Common  Stock  issuable
pursuant to the Company's 1997 Stock Option Plan (the "Plan").

     In acting as such counsel and for the purpose of rendering this opinion, we
have reviewed copies of the following, as presented to us by the Company:

         1.       The Company's Articles of Incorporation, as amended.

         2.       The Company's Bylaws, as amended.

         3.       Certain corporate resolutions adopted by the Board of 
                  Directors and shareholders of the Company pertaining to the 
                  adoption and approval of the Plan.

         4.       The Plan.

         5.       The Registration Statement.

     Based on,  and  subject  to, the  foregoing  and upon  representations  and
information  provided by the Company or its  officers  or  directors,  it is our
opinion as of this date that:



         1.       The Shares are validly authorized by the Company's Articles 
                  of Incorporation, as amended.

         2.       Upon  issuance and delivery of the Shares  against  receipt by
                  the Company of the  consideration  for the Shares  pursuant to
                  the terms of the Plan,  the  Shares  will be  validly  issued,
                  fully paid and nonassessable.

     We hereby  consent  to the  filing of this  opinion  as an  exhibit  to the
Registration Statement.

                                               Very truly yours,

                                               FREDRIKSON & BYRON, P.A.



                                               By  /s/ Timothy M. Heaney
                                                  Timothy M. Heaney