In one aspect, the present invention provides: a pharmaceutical composition for preventing or treating erectile dysfunction comprising a modified DKK2 polypeptide or a nucleic acid coding same and a method for preventing or treating erectile dysfunction in an individual, the method comprising a step of administering, to the individual, the modified DKK2 polypeptide or the nucleic acid coding same. Accordingly, the composition and method can be used to prevent or treat erectile dysfunction in individuals.