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                                                                    Exhibit 5.01


                                [NSP LETTERHEAD]


                                November 20, 1998


Securities and Exchange Commission
450 Fifth Street NW
Washington, D.C.  20549


         Re:      $400,000,000 principal amount of First Mortgage Bonds,
                  Senior Notes and Debt Securities of Northern States Power
                  Company, a Minnesota Corporation


Gentlemen:

         I am participating in the proceedings incident to the issuance and sale
by Northern States Power Company, a Minnesota corporation (the Company) of up to
$400,000,000 principal amount of First Mortgage Bonds, the New Bonds, Senior
Notes and Debt Securities (collectively, the "Securities"). I have examined all
statutes, records, instruments, and documents which I have deemed necessary to
examine for the purposes of this opinion.

         Based upon the foregoing and upon my general familiarity with the
Company and its affairs, I am of the opinion that:

         1.       The Company was incorporated and is now a legal existing 
                  corporation under the laws of the state Minnesota; has 
                  corporate power, right and authority to do business and to 
                  own property in the States of Minnesota, North Dakota and 
                  South Dakota in the manner and as set forth in the 
                  Registration Statement, Form S-3, to which this opinion is 
                  an exhibit; and has corporate power, right, and authority 
                  to create, issue, and sell the Securities.

         2.       When and if (a) the above mentioned Registration Statement 
                  has become effective pursuant to the provisions of the 
                  Securities Act of 1933, as amended; (b) the Minnesota 
                  Public Utilities Commission has issued its order approving 
                  Capital Structure which permits the Company to issue the 
                  Securities; (c) the Supplemental Indenture relating to the 
                  Securities, has been duly authorized, executed, delivered, 
                  filed and recorded as required by law; and (d) the 
                  Securities have been duly authorized, executed, 
                  authenticated, and delivered and the 


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November 20, 1998
Page 2

                  consideration for the Securities has been received by the 
                  Company, all in the manner contemplated by the said 
                  Registration Statement, the Securities will be legally 
                  issued and binding obligations of the Company and, with 
                  respect to the New Bonds, will be entitled to the benefits 
                  and security of the Company's Trust Indenture, dated 
                  February 1, 1937, as supplemented.

         3.       The statements made in the above mentioned Registration 
                  Statement and related Prospectus, purporting to be made or 
                  based upon the opinion of counsel, correctly set forth my 
                  opinion upon said matters.


                                            Respectfully submitted,


                                            Gary R. Johnson
                                            Vice President and General Counsel


