There are provided, according to the present invention, a method for producing a cis-3-substituted-3-azabicyclo[3.2.1]octan-8-ol derivative, the method characterized in that a trans-3-substituted-3-azabicyclo[3.2.1]octan-8-ol derivative or a mixture of the trans- and cis-3-substituted-3-azabicyclo[3.2.1]octan-8-ol derivatives is isomerized in the presence of an aluminum compound represented by a formula Al(OR1)3 (wherein R1 represents a hydrocarbon group in which a carbon atom having an oxygen atom bonded thereto is a secondary carbon atom). In the process, a ketone compound may be further added, in addition to the aluminum compound.